Re: Service Engine Soon LIght "Code P0400" ????? (Rome856)
The quick way to diagnose this - clear the code. then, start the car. If the code comes back immediately, then its the control valve, if it takes a while, its the EGR itself.
you see, the computer will sence a bad control valve during initial self test at startup, but it won't find the EGR until it goes into closed loop...