I wanted to pass along some information that will affect a large number of vehicles, 5 years worth actually.

Pretty much every NA (naturally aspirated) 4 cylinder model from 2006 to 2010.  Essentially the front air fuel sensor is not correctly reaching operational temperature early enough in the start up cycle and until it does the content of the emissions coming out of the tailpipe will be increased over the design.  I do think its great when something that affects our air quality is recognized and dealt with properly such as this.

2006-10MY Legacy, Outback, Impreza & Forester

Subaru of America, Inc. has initiated a Service Program to reprogram the Engine Control Module

on certain 2006 – 2010 MY Legacy, Outback, Impreza & Forester vehicles with 2.5 Liter normally

aspirated engines. Models with 6 cylinder or turbo charged engines are NOT affected.

A modification to the ECM software logic has been developed to improve the performance of the

emission control system. This software change will not adversely affect fuel economy or

performance.

This software update is intended to improve vehicle emissions when the vehicle is operated in

cold weather and the engine is turned off and restarted within short periods of time such as in

several minute intervals. The A/F sensor contains a heating element, which is controlled by the

ECM, and which assists the sensor in reaching an optimum temperature, resulting in better

accuracy. When the vehicle is operated under the conditions described above, there could be a

longer than desired delay in the ECM’s turning on the A/F sensor heating element, resulting in

higher than desired emissions. This software enhancement will correct that condition.

ECM reprogramming PAK files will not be available for all models at the time this Service

Program is initially released. PAK files will be available in accordance with the schedule found on

page 4 of the WVU-31 bulletin.

Now because the service campaign will affect a huge number of vehicles Subaru is going to trickle out the letters to Subaru Owners, however if you are taking a vehicle affected in for service you should inquire about having it done to avoid having t make a second appointment when your letter comes.

Thanks for reading

Justin