EGR 402 Excessive Flow

#1

07 6.6L Turbo diesel keeps popping EGR 402 codes. GM cleaning procedure

done ($90). EGR Valve replaced (free). No codes for a couple weeks then

bam… three times in the last week. Reset with code reader each time to

see if it was a stray code or a real problem. So what to do next? The

dealership should be responsible at this point for tracking down the

problem, but apparently they don’t know how.

#2

Is there some kind of solenoid that controls the EGR valve? That’s where I would suspect next. Could be just a flaky connector.

#3

how about the flow sensor itself?