Your Subaru Check Engine Light Explained
November 8th, 2007 by Justin Stobb | 46 responses
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The Check Engine Light explained
Starting in 1996 all passenger vehicles and light duty trucks produced or imported for sale in the U.S. had to be OBD II compliant (On Board Diagnostics two). As well as meet newer vehicle emissions regulations. Part of this technology involves the check engine light or MIL. (Malfunction Indicator Lamp). While it’s true that prior to 1996 the check engine light did exist on vehicles, it took on an entirely new meaning and purpose in 1996.And this is where the confusion starts.
The check engine light comes on when the ECM (Engine Control Module) recognizes a malfunction with an emissions control device or an emissions control device monitoring system or if a specific condition is not being met. In many cases the vehicles overall performance won’t change much if at all when the light comes on, and is thus not taken seriously by the majority of car owners. But what the light represents is a potential failure in one or more of the vehicles systems that are meant to control the level of tail pipe and evaporative emissions produced to acceptable levels. In some cases the light can come on when the gas cap is loose. But the light can also come on when the catalyst system has failed.
Normally neither one will adversely affect the vehicles performance but both will allow the vehicle to excessively pollute our environment. The gas cap is meant to keep the fuel vapors sealed in the tank and evaporative emissions system rather then allowing the fuel vapors to enter the atmosphere as hydrocarbon emissions. The catalyst system is designed to lower tail pipe emissions to acceptable levels. These are just two examples of many possibilities.
There are essentially two types of OBD II Fault codes, conditional and component. A component code usually indicates a problem with a particular device, its circuitry or controls. A conditional code is set when a specific condition triggers the ECM to Command on the check engine light. Conditional codes are the hardest to accurately diagnose and repair and are typically the ones that do the environment the most harm. It is almost impossible to accurately diagnose and repair a conditional code with a code reader from a local parts house. It is simply not enough to have the code number but rather a thorough analysis must be performed by a qualified professional technician.
When a code is cleared, the emissions systems monitors are also turned to not ready status. It takes a specific drive cycle to return the monitoring systems back to ready status and the whole time the monitors are off they are not monitoring the emissions control devices. This is why sometimes a code can be cleared and not come back for weeks. Until the monitoring system is back to ready status the ECM doesn’t know about a device or a condition.
Specializing in Subaru repair gives us an advantage over other general repair shops when it comes to the diagnoses and repair of the check engine light and vehicle emissions systems on your Subaru. We will accurately diagnose the failure, any potential causes of the failure and keep you informed the whole way through. More importantly we can provide you with tips to help reduce the amount of emissions your vehicle emits and keep you an informed Subaru owner.
The above was prepared and written by.
Justin Stobb
Owner All Wheel Drive Auto
ASE Master Certified Technician, L1 Advanced Engine Performance Certified
WA. State Dept. Of Ecology Authorized Emissions Specialist
The Author: Justin Stobb
About: All Wheel Drive Auto is a unique independent Subaru service & repair facility. We combine years of dealer experience with a local neighborhood shop atmosphere. We use Subaru parts & test Equipment and have the expert knowledge to fix it right the first time.
This entry was posted by Justin Stobb, on Thursday, November 8th, 2007 at 5:29 am and is filed under All Wheel Drive Auto News, Blogroll, Subaru Maintenance, Subaru Repair Seattle. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response on the right, or trackback from your own site.
June 25th, 2008 at 8:31 pm
I live in Crestline California and our community has a large amount of Subaru Outbacks on the road. Everyone that I know that has a 2000 has their check engine light on. We have had the codes checked and random issues that are not resolved even with replacing parts. When 6-10 people experience there is a design flaw.
June 26th, 2008 at 12:34 am
Craig,
Please remember I am unbiased and only trying to factually educate you and other readers.
A check engine light can come on because the driver puts gas in the car and did not tighten the gas cap up. How is this design flaw? It is mandated by law by the Department of ecology.
The check engine light is geared towards alerting the driver when the computer sees a problem with the vehicles emissions system and there are Thousands of possible reasons for the light to come on.
Just as there are a thousand reasons you might have a headache but bottom line the only thing you know is that you have a headache or a check engine light is on. If taking aspirin doesn’t fix your headache is your body a design flaw? Or was your headache not diagnosed properly or maybe there are a number of things contributing to your headache as your whole body is aging at the same rate of speed. Just like every part in your car is the same age and guess what, things are going to fail in unison.
If a check engine light comes on and a code number P0325 Knock sensor circuit is set, and then diagnosed by a pro, not a code scanner at your local parts store, the P0325 should be satisfied once the properly diagnosed condition is repaired causing the code P0 325. If the check engine light comes back on a week later and now its P0440 Evaporative emissions system leak detected that is a new problem that must be diagnosed by a pro, it may be the gas cap is loose but it may also be that the purge canister has a leak also.
Due to how the emissions system works not every system is monitored by the vehicles computer every second the engine is running but rather when a specific event is met. You can look online for an OBDII drive cycle and see what I mean. You can ATTEMPT to fix a problem but it may be weeks or months before the computer actually has the proper monitor turned back on to ready status. Until the monitor is ready the computer does not have the ability to command on a check engine light based on a failed component or condition triggering a code.
Typical problems with the 2000 Subaru Outback that will trigger a check engine light are a failed knock sensor, failed Catalyst system, failed front air fuel sensor, failed rear 02 sensor, loose gas cap.
Every one of these items fails just as often on any other Japanese import as they are almost all made by the same vendor first of all and subject to like environments in which they can become damaged.
If a check engine light is diagnosed and comes back on for the same reason aka a reoccurring PO325 then the diagnoses was wrong or incomplete. If the light comes back on and it is a different code it’s a different problem.
The real problem is that the parts stores try to devalue the real skill and knowledge it takes to truly diagnose a car, as does franchised auto repair shops such as the Tune and Tire centers.
If you take your Subaru to a Independent Subaru expert and your neighbors and friends alike the experience will be different or hopefully after reading this you may better understand it’s a complicated process sometimes not a design flaw.
Do also remember that the goal is to try and clean up the environment.
If you are driving your Subaru around with a check engine light on you may not be doing your part to help
October 8th, 2008 at 4:44 pm
Dear Justin,
Thank you for your informative response. We own a 2001 Subaru Outback Limited and live in Central California. The “check engine light” went on the first time we drove the car after a month’s vacation (sans Subaru). Unfortunately, I need to have a smog check for registration purposes. The smog check people told me the car would fail the smog check with the check engine light on and that they would “diagnose” the problem for $80, in addition to the $40+ charge for the smog check. After reading your article, it seemed to me that for $80, the smog checkers would just disable the monitoring system, run and pass the smog check, but not “fix” or accurately diagnose the problem. I originally bought the car in Washington State and we are driving back up there this week. After buying gas and tightening the gas cap (do I need to reset anything?), I am thinking of driving up to Washington to have the car looked at. We have a good, honest mechanic up there. What is your advice? Thank you.
October 10th, 2008 at 4:43 am
Hi Ellen,
So the monitors have to be on to pass the emissions test in Washington state as the car is tested at test station and not at a shop.
I cant really speak as to what the smog station in California would be testing or just how good their analysis would be
If the check engine light comes on and sets p0440 evaporative emissions system leak and the gas cap is found to be loose, tightening up the cap and a few drive cycles with the(ECM) Engine Control Module seeing no failure to pass the test the ECM will turn the light off.
A flashing check engine light means stop driving the car, a check engine light on steady, means proceed with caution.
It is hard to tell you if you should drive it from there to here with the light on or not. The code number at a minimum would be a good starting point to know how to best advise you.
Most parts houses will offer to connect a generic OBD II scan tool up to your car and tell you what code is set for free. Maybe start there, drop me a line when you get the code and we can go from there.
Justin
November 23rd, 2008 at 9:58 pm
My check engine light on my 1996 Subaru Legacy Brighton recently came on and stayed on. I took the car to my local mechanic who ran the obd 2 scan tool. The code came back as a number 4 cylinder misfire. My mech called me and advised to start by replacing the plug wires. I went to the mech shop to pick up my veh after hours as shop had already closed. Once I started the vehicle my check engine light now flashes ocnstantly and will not stop. I have checked all of the fuses that I can find and all appear to be ok and have unhooked and rehooked the battery to reset the light. I went ahead and replaced the plug wires as directed but no change. Will note that the cooling fans run with the key turned “on” but not started and can hear the fan relay clicking. Once the veh is started the fans turn off until veh heats up. I have not noticed any problems with running the veh or any missing. The only problem now seems to be with the constantly flashing check engine light. I have searched all avail websites and can not find any useful info. Please help if you have any idea what could cause this to occur. Thanks.
November 23rd, 2008 at 10:41 pm
by the way, i kept reading the q and a’s and found that the green “d-check” plug was hooked up. the shop is closed today so i can not ask them if they hooked it up or not to run the obd 2 scanner. once the plug was unhooked, the ce light stopped flashing. even though i have not received a reply i can say that this site truly helped. thanks.
November 24th, 2008 at 3:33 am
Glad we could help in some way
December 16th, 2008 at 8:33 am
i have a subaru legacy GL 2.0 1999 ….
which shows the check engine for the 1st time
checked it and says
22 Knock sensor
so i went to the dealer and buyed it for 50$
replaced it and start the engine but the check engine ligth is still there w8in for me….
i checked it agine and it sayes
22 Knock sensor
which is replaced the same day !!!!!!!!!!!!!
what can i do to remove this check engine light???
help 911 !!!!!!
plz need a help soon
December 29th, 2008 at 9:06 pm
Hi, I have a Subaru legacy GT 2.0 2001 which has been showing the check engine light for a while now. Sometimes when I brake or accelerate it goes off but will come back later when I restart the car. My front brake pads were worn out but I replaced them, now my left brake bulb is not lighting could this be the reason for the check engine light coming on?
January 15th, 2009 at 4:41 am
I have a 2006 Subaru Impreza Outback Sport with 40000 miles. After a drive on the highway today (about 140 miles round trip) my car started to shake when idling. I assumed it was because fuel was low and was on the way to get gas anyway. After filling the tank, the stutter when idling continued and thecheck engine light began to flash. When I turned the ignition off, the vehicle had a strong burning rubber smell. Any thought on whether it is safe to drive to the dealership at this point to have it checked out and whether this is something covered under warrantee?
January 15th, 2009 at 6:51 am
Hey Erica,
You have a misfire and you really should have it repaired, a flashing check engine really does mean to stop driving the car. You can do damage by driving it to far and too long with a cylinder misfire.
Most likely it is a failed ignition wire or spark plug neither are still under warranty, there are of course other possibilities and I am really only advising you on the most typical things we see.
Justin
January 22nd, 2009 at 6:28 am
I have a subaru Legacy Brighton 2000,and of course the CEL is on .Since I can smell exhaust inside the car.
I am going to buy a scanner ,could you tell me where to plug it in?.Also just for info, after 160000 miles the clutch is the original one.Thank you for your time.
Francois
January 24th, 2009 at 6:48 pm
You want to connect the scanner to the OBDII connector on the drivers side under dash area.
A scan is only the beginning mind you.
February 22nd, 2009 at 6:22 am
I have a code P0420. Do I replace the sensors first or just bite the bullet and replace the catalytic convertor? If replacing the cat is it Okay to replace with a universal catalytic convertor which is far cheaper or buy the OE one? Any ideas would be greatly appreciated.
February 22nd, 2009 at 7:20 am
Hey Keerthy
I would test the sensors and if they are slow to respond to forced mixture changes I would start there. I would also try to increase the exhaust temperature for a while afterwards to try and burn out any contaminants in the catalyst.
The aftermarket cats seem to last just about one year they are cheaper only as a result of having less precious metal in them which affects the performance and longevity.
Justin
February 22nd, 2009 at 11:36 pm
Thanks Justin. I dont know if its okay to post the question in this thread but here goes.
My 97 Legacy Brighton MT is in the shop to replace the clutch and has 192K miles. Recently acquired and I have no service history, what are the things you suggest changed at this point?
It is a 2.2L H4. Steered clear of the 2.5 because of the headgasket issues.
I came across this website after the car went to the shop else I would have brought it to you since I live in redmond.
Will come by for an inspection after I get the car back from the shop as I live in redmond.
P.S : Please feel free to move the post if it is inappropriate here.
February 27th, 2009 at 7:10 pm
I had a problem with my CEL staying on for several months in my 2005 Subaru Outback, even after having a diagnostic test at a Subaru dealer and replacing the left fuel-air sensor which the test showed as weak. Solution in this case was simple: buy only gas that has no ethanol in it. Shell or Exxon has no ethanol in it. The boxer engine doesn’t burn hot enough to remove ethanol from the air/fuel and oxygen sensors, so the CEL goes on (and your cruise control goes off!). Since filling up with Shell my light has been off for good. It may take two or three tankfuls, but is sure works well!
March 21st, 2009 at 3:28 am
Hi,
I have a 2002 Subaru Legacy. The CEL has been on for several months. Autozone told me the code is P0420. My husband looked under the hood last week and found that the coolant is completely dry in the reservoir. Dried up coolant had happened before, but I kept forgetting to check often.
What can cause the coolant to be depleted? Is this related to the CEL and code P0420? Should I have the cat replaced?
March 21st, 2009 at 3:40 pm
Hi Mel,
One of the most common mis diagnosed codes is PO420 a code reader from Autozone is just that a code reader. The value in the diagnoses is the same as you have paid for it. Having the code only tells which code the computer is setting in connection with the light coming on.
PO420 is set on every car when the computer does not see a significant increase in the oxygen levels in the exhaust as it travels through the catalyst. A properly functioning catalyst will convert some of the carbon monoxide created in the combustion process of the engine and convert it to oxygen.
There are many things aside from the catalyst that can cause a catalyst code.
My guess based on the coolant loss is an internal head gasket leak allowing some coolant into the combustion chamber and thus into the exhaust system.
But I am not clear on how quickly does it loose coolant?
The water in the coolant will evaporate and does need to be topped off at every oil change interval at a minimum.
IF you want the right results I would seek out a good independent Subaru shop in your area and let them diagnose it locally rather then just replace parts without a real diagnoses.
Justin
March 21st, 2009 at 10:44 pm
Hi Justin,
Thank you so much for your knowledgeable response. I wish I lived in Seattle so I could take my car to your shop. The local Subaru dealer here only wanted to replace the cat per PO420 code without any diagnostic tests. Thus, I have not been willing to let them do that.
The first time the coolant went dry was November 2008.
Today, the battery went dead and Walmart replaced it as well as the terminals.
April 6th, 2009 at 10:35 pm
I have a 2001 Outback limited with about 95k miles. I had a CEL that was reading misfire in cylinders 3 & 4. I started with spark plugs. No change. I then did wires. Still no change. I switched out the ignition coil for 3/4. Things were good for about 10 days and now it is coming back on with only a misfire in #4. I am trying FI cleaner and Lucas oil fuel system treatment, hoping that a possible FI clog will be the cause. Any other ideas on what I should look at? The car runs smooth and I feel a VERY slight vibration when cold and at idle. Thanks!
April 10th, 2009 at 11:00 pm
I was wondering if anyone might be able to help me. I have 98 impreza 2.5RS, and I am going through my yearly inspection in NY state. I have a code reader for my OBD2 and I am able to see the codes and erase them. My question is, how do I clear the incompletes from memory, after I erase the codes. I heard three driving cycles or 200 miles without setting the CEL off. If anyone knows exactly what a driving cycle consists of, or if my information is correct, please let me know! Thanks.
April 13th, 2009 at 9:42 pm
Regarding “D-connector” or “D-check” plug and CEL:
I recently bought a 2007 Subaru Outback. I noticed a green connector on the passenger side, under the glove compartment, just above where the floor carpet stops. Thinking it should be plugged in, I connected the two sides together. The CEL came on. To make a long story short, with the green plug connected, error codes P1518, P0851, P1152, P1153, and P0140 all showed up when I went to a local parts store and they hooked up a computer. I disconnected the green connector and the computer showed “pass” on everything/no error codes. I called local Subaru shop and they explained this green connector is called a “D-connector’ or “D-check” plug, and it is supposed to be DISCONNECTED. Apparently they have to connect it to do some kinds of tests in the shop, but otherwise it is supposed to be DISCONNECTED. Maybe everyone else already knows this, but it took me a lot of searching and anxiety to find this out, so I hope this information will be helpful to someone else.
April 15th, 2009 at 12:41 am
My engine light came on this afternoon. It was suggested that the gas cap might be the problem. When I checked it I discovered that it was not on tight. When I started the car the engine light was still on. I have been in a panic afraid to drive my car and afraid of how much I may have to spend to get it corrected.
Your article gave me such a sense of peace and a good feeling that I can better describe my situation to the service department!
Thank-you! I hate all this computer stuff in cars but I still ove my subaru!
Jan
April 17th, 2009 at 9:24 pm
Regarding “D-connector” or “D-check” plug and CEL:
THANKS Tony!!! That has been driving me crazy. That is something that needs to be labeled and/or called out in the owners manual. I just went through the same experience today, Yours is the first piece of info I could find on it. Again, thanks for doing the legwork.
April 27th, 2009 at 3:57 pm
97 postal legacy.. does speed sensor 2 input to ECM and if not working could it produce rough running and stalls?
May 2nd, 2009 at 6:32 pm
T Robert,
Speed sensors do not typically cause a rough running issue on a Subaru.
Justin
May 11th, 2009 at 3:56 pm
95 legacy 2.2L engine light on, code reads misfire in 3 and 4. New coil,wires and plugs. Found Corrosion under ignition module, cleaned it, fixed problem for about 1000 miles. Could ignition module be problem or maybe crank senor? I think I’m close to the problem…. hoping it isn’t the cam. I have 240,000 miles and hoping for more:)
May 12th, 2009 at 5:37 pm
Hey Kent,
I would drop the exhaust down and inspect the exhaust valve guides to see if they have “shifted” Very common if it has single port exhaust.
Justin
May 13th, 2009 at 1:56 pm
Justin
I read about that after I wrote you. What is the fix if the valve guides have shifted. You mentioned sticky valves from sludge between stem and guide. Suggesting an oil flush and synthetic, and lube guard. Should this be done also/anyway? This is a very informative sight. Also, I read that the oil pump return hole is to small and should be 6mm, causing an oil leak between pump housing and cylinder block sealing surfaces…. should I worry about this? Wondering if the burnt smell we get is from that and/or missfire. Thanks again for the great information.
Kent
May 26th, 2009 at 5:25 pm
Kent,
If the guides have shifted it requires machine work to the heads, installing oversized OD guides and a valve job.
If the valves are just merely sticky than a fuel induction service may help.
Justin
June 12th, 2009 at 4:38 am
Justin,
Thanks for the good info here. I have a P0420 cat code on a 2002 Forester, and there definitely seem to be many possible causes. I read the o2 sensor voltages over OBD2 with the engine at operating temp and found that sensor 1 runs at 1.5 volts and does not change. The OEM Bosch part is spec’d for 0v - 1v. Does this mean the sensor is broken, fouled, or the cat is bad?
June 13th, 2009 at 5:05 pm
Jeremiah,
Which sensor are you looking at the first or second, also 02 is a split year in the Forester platform and the front 02 sensor is also referred to by Subaru as a air/fuel sensor and works in a different range as the 02 sensor does.
June 16th, 2009 at 4:48 am
Justin,
The OBD2 tool specified bank 1, sensor 1. I’m not sure which that means. What range does the air/fuel sensor work in?
As a follow up, I drove the car a little harder on advice from friends that hot exhaust is occasionally needed to keep carbon buildup out of the cat and off the O2 sensors. The engine started overheating, and when I checked there was no coolant in the overflow. My girlfriend (car owner) said the tank never holds coolant for more than a day, so she just fills it once in awhile. I filled it and it did not leak overnight. I suspect a leaking head gasket is fouling the O2 sensors with coolant in the exhaust. Any thoughts?
Thanks for the help!
June 16th, 2009 at 12:39 pm
i have a 02 outback and had to have the engine replaced in it in November ‘06. The engine was replaced at a subaru dealership and since then i have had a “check engine light” on. I returned it to the garage and they cleared the codes and said it was fine…sure enough it came back on and i brought it to a different subaru garage and it was cleared TWICE and still is on. they said there was just a wire malfunction and it was no big deal….fast forward 2.5 years ahead (still the engine light is on this whole time) and now i just went last weekend to get the car inspected and the subaru dealership that replaced the engine, has inspected me for two years- wont inspect it because of the light. they said the state has changed thier standards and will not pass it ….so my question is what do i do??? i have been driving it around for over 2 years like this and two subaru garages can’t fix it and now they wont give me an inspection sticker!!! i have 60 days to “fix” the problem.
June 16th, 2009 at 12:42 pm
oh i forgot to tell you waht codes come up! the cylinder 3 misfire and the theshold…i cant recall the exact code numbers but they are the same two that have come up since the engine replacement in ‘06.
June 16th, 2009 at 10:27 pm
Gina,
If a check engine light is temporarily turned off and then comes back on as soon as the vehicle’s computer sees a problem then obviously something is wrong.
I don’t understand why any Dealer service department would tell you it is ok to drive around with a check engine light on as it contradicts what is written by Subaru in your owner’s manual.
I could go on for an hour or two about this and also why it’s always bad to involve a bunch of different shops, in your post you mention “the garage” have you been taking to a Subaru Dealer service department? I wasn’t clear on that part.
Enough of what could and should have been done a while ago. The car is very fixable, but yes it is going to cost to have a real pro look at it, diagnose the real issues causing the codes that are set at this time and once that is done it is very possible for the light to come back on with new codes set. There are many codes and only one light. Add to that for each code there are many possible reasons for that code to be set.
Driving around with a misfire code is never good, as to the Catalyst efficiency code there are a lot of reasons but if it has had a misfire for any length of time the catalyst is probably damaged as a result or may have been affected from the previous engine failure.
If the Subaru has been taken to the Subaru Dealer service department on all of the occasions you have mentioned I would call SOA or at least have an in depth conversation with the Service manager at each Subaru dealership.
I do want to stress though that you will want to look at the invoices from when the car has been looked at and look to see if there is documentation as too which codes have been set each time and were there any suggestions made that were not performed?
What really needs to happen is a real diagnosis of the problem and corrective repairs in correlation with the diagnoses.
Now I don’t know the Emissions laws in your state or which state you are located but some states will substitute a tail pipe test in lieu of an OBD test when there is a catalyst code set.
Justin
June 20th, 2009 at 4:22 am
Justin,
My 2001 Forester had a stumbling at idle diagnosed as bad spark wire (replaced by dealer) CEL came on, temporarily off with upper cylinder cleaner added by dealer, back on with knock sensor code, sensor replaced by dealer, engine gasket leak, coolant loss, replaced by dealer, CEL on again. Gas cap tightened always. Car drives perfectly. What’s your guess?
June 23rd, 2009 at 4:03 pm
Allen,
There is just no knowing without at least the code information. Most likely a P0420 Catalyst code if I had to guess.
Justin
June 24th, 2009 at 3:37 am
2000 outback runs like a dream but CEL comes on every once in a while…stays on and then disappears. Code is P0328 KNock sensor 1 Bank 1. Right now i have not seen the sensor for a week. i wonder if the ethanol in the gas is the culprit? any thoughts
June 24th, 2009 at 5:49 pm
Brian,
The knock sensors on that era Subaru are very prone to failure; it’s not an expensive fix by any means. The knock sensor will emit a frequency back to the ECM when the vehicle pings, the computer will use this information to advance or retard ignition timing for the fine tuning of the engine. There is a little more to it than that, but that is the basics of how it works. A failed knock sensor will cause the ECM to go into a fixed or programmed set of timing values based on other data rather than constantly looking to fine tune the engine. So while it may seem to be running ok, you could affect fuel economy a small amount and an engine that is running as good as it possibly can, will always outperform one that is in need of tuning.
Hope that helps
June 30th, 2009 at 5:42 pm
Hi, thanks for this great forum.
I have a 1999 Forester, the alarm/auto doorlock system had been acting like it was possessed for a long time, it was a minor annoyance and sort of amusing, (pass a police station or hospital and the alarm would *bleep* and *bloop* and all the locks would lock and unlock rapidly, making a machine gun-like sound), in any case, some time ago the car wouldn’t start, I had it towed to my mechanic who diagnosed a grounding problem with the ignition. He ran a new grounding wire and all seemed right with the world. although the next day the MIL came on. I need to take it to get the emissions tested and so brought it to the mechanic again and the scanner came up with code P1101 which he said was “Neutral Position Switch Circuit Malfunction (M/T)” Thinking that this had to do with the shifter lockout system and in my mind connecting that with the crazy alarm system I then had an auto alarm shop pull the alarm completely out of the car. Now the MIL is *blinking*, took it back to the mechanic, but the codes are not related in any way to the ECM that I can tell, they are: P500, P1101, P1121, and P1540.
The Internet tells me that these are:
P0500 - Vehicle Speed Sensor Malfunction
P1101 - Neutral Position Switch Circuit High Input (A/T)
P1121 - Neutral Position Switch Circuit High Input [MT Vehicles]
P1540 - Vehicle Speed Sensor Malfunction 2
OK, so I think I should have a question … how about: Why would the MIL blink if none of the codes being reported have to do with emissions or damage to the Catalytic Converter? Can I get the car tested and if they see that the codes are not related to emissions that they’ll let me pass. OK, I know that’s not going to happen, but argh.
Thanks again for the great forum!
–
max
July 1st, 2009 at 10:49 pm
Max,
It’s hard to really understand all of the issues you are having, I am afraid you really need to take this car to A Subaru Experienced Technician preferably a good Independent Shop.
Here is really all I can offer over the internet.
The neutral switch on the manuals fails quite often, but will not cause a check engine light to flash.
There is no way to circumvent the system especially with a flashing check engine light.
Some of what you have written doesn’t really add up? Not sure how a ground was affecting the ignition switch that would be very unusual unless it was related to the alarm system. I suspect a cheap aftermarket alarm wasn’t installed correctly from the start and then the removal wasn’t done properly at all either some alarms have auto locks based on vehicle speed and if the speed sensor wires were tapped into incorrectly that would be very bad. Does the Speedometer still work? I suspect the code numbers aren’t accurate either and a generic scan tool is being used and not a real Subaru Select Monitor. Has anyone looked at/ diagnosed/tested any of the sensors/ switches in question?
Probably a good Idea to have it looked at.
Justin
July 2nd, 2009 at 4:15 pm
I guess i have a similar problem with my engine light just went on today…and i’ll check gas cap? I’m on vacation though and wondered if i could drive my car 400 miles if the light is on…i really would like to check out the problem at home…unless the light goes off after i check the gas cap.
July 2nd, 2009 at 4:16 pm
Forgot to say it’s a 2004 Forrester.
July 2nd, 2009 at 4:39 pm
David,
After inspecting the gas cap, if you have found it loose it will take a few drive cycles before the computer will clear the check engine light. It may be wise to have it scanned at a parts store since you are on a road trip, most of the time it is just a drive with caution kind of a thing but there are a few codes that can be set in correlation with bigger problems that should not be ignored. At least knowing what code is set is a good thing to know before getting back out on the road.
Justin