I have a 1998 outback, the engine light is on, I have taken it to the shop, the computer show code 00400 an EGR valve problem, I have changed it out and the problem still exist and my machanic is stumped, and ideas? not effecting the proformance.
Was anything actually checked or tested before just changing out the valve? The code doesn’t say that the valve is bad - only that there wasn’t enough exhaust going into the cylinder. This can happen for several different reasons.
Check this out to move forward: http://www.obd-codes.com/p0400