Subaru of America, Inc. has determined that vehicles affected by this Service Program require ECM...

Bulletin number

WQW-58R

Component

Engine and engine cooling

Summary

Subaru of America, Inc. has determined that vehicles affected by this Service Program require ECM reprogramming. This bulletin includes the service procedure for diagnosis and repair of customer concerns involving engine idle roughness or, in some cases, engine noise and/or damage resulting from spark knock (pre-ignition). The Engine Control Module logic has also been optimized requiring the ECM reprogramming. The new logic optimizes the ECM for control of the following parameters: Change to Fuel Cut control when fuel level is extremely low / near empty Change to improve idle smoothness / quality Change to boost pressure control under wide-open throttle (WOT) conditions. Under certain high engine load driving conditions, spark knock can occur which results in elevated cylinder temperatures and pressures. Over time, excessive erosion of the spark plugs and possible damage to the pistons can be consequences of continued operation with these conditions present.

Owners of these vehicles have filed 226 complaints in the engine category.