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