The head gasket has a high failure rate due to cooling system problems. Subaru is aware of the problem and has extended the warranty to 8 years/100k miles on many vehicles.
Resources for the Repair and Maintenance of your 2004 Subaru Impreza Outback
2004 Subaru Impreza Outback
2004 Subaru Impreza Outback Problems
The Check Engine Light may illuminate because of a failed knock sensor. Although the sensor often tests okay, it can fail intermittently, while the vehicle is being driven.
Sometimes the Check Engine Light illuminates because the computer detects misfires. Subaru released an improved spark plug wire set to solve the problem. The ignition coil should also be inspected for carbon tracks or short circuits between the contacts
There is a technical service bulletin on the ABS control module. It is replaceable without having to replace the entire anti-lock brake hydraulic unit. Previously, the ABS control module was only available as a complete assembly that included the hydraulic unit.
2004 Subaru Impreza Outback Questions and Answers
hanger and the baffle. Will need a new center pipe and muffler/flang Cost $1082.
Can I get it done with Subaru parts at none Subaru shop?
Is Meineke Car Care Center in Norwood Good? Or is bett...
Dealer says it is because the independent mechanic I get service at does not add the Subaru additive during a flush and fill and encouraged me to use dealer for service. I can't afford the de...