Originally posted by Rayn:
I have P0402... I also have the diagnostic paper with the description/possible causes/diagnostic aides. There are 10 different possible causes... The mechanics quoted me around $250 for the repair (diagnostic test was free).



If the idle is good replace the DPFE.

If the idle is bad, pull the vacuum to the EGR valve. If the idle is still bad, replace the EGR valve.

Plug the vacuum back in from above step. Unplug the elecrtical connector from the EVR. If the idle stays bad, replace the EVR. If the idle gets better, replace the DPFE.


If the EVR is still opening the EGR valve, you either have an EVR wiring problem or false output from the computer.

My bet is on the EVR. If the EVR starts leaking the EGR valve will stay open.

"Those who cannot remember the past are condemned to repeat it" -George Santayana