Could be one of the following:
- lack of vacuum at the egr valve due to either a leak in the vacuum hose, or a defective egr solenoid.
- Carbon build up in the valve or the egr tube.
- Defective DPFE sensor or plugged DPFE rubber hoses
- Busted egr tube
- Defective egr valve, or egr gasket.
It appears that most of the time, the culprit for this problem is a bad DPFE sensor.
Thursday, April 9th, 2009 AT 11:09 AM