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You have helped me once before.. and thanks. I received the above code and have changed the DPFE modual (the new one is plastic) but the Check Engine light did not go out. I cleared the light but both the light and code came back. I plan on changing the EGR sensitivity sensor (the one with the round top) since it is the next in line from vacuum to EGR... with EGR next. Will the light go out by itself or will it need to be reset. By the way, I CALIF smog tested it (for registration)... if passed everything but the Check Engine Light so it failed overall. All numbers were WAY within limits. Thanks in advance for your help! Don
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Hello and thanks for the question...I'll try to help.
The codes need to be cleared using a scan tool.....just disconnecting the battery won't do it. Also, if the CO, CO2, HC, and NOx were all with in the limits, I wouldn't think that a sensor is out of range.
Hope this helps,
Erik
-- Erik, is the scan tool the same as the ODBII reader/reset that I have (and used to reset) or is it a more advanced tool? I did reset the light but about 10-15 miles later the code reappears and the light comes back on about 5 miles later. Is it possible the problem is fixed (with the change of the DPFE sensor) and it needs a more advanced reset -- or is my ODBII reader the scan and something else needs to be replaced. If so, what are your suggestions? Thanks!
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Hello and thanks for the reply...I'll try to help.
The OBDII tool you are using should be fine for the reset. I've never seen a problem with generic tools clearing codes. Does the same code come back after resetting the system? What you might want to do is see if the scan tool that you are using has live read data capibilities....see what the O2 sensors and EGR system is doing.
Erik
Erik,
I really appreciate the time you are taking with me on this issue.
1) Yes, the same code (P0401)continues to reappear (although I have not really driven it until all tests show as completed... I am doing that next.
2) I have now changed the DPFE, the sensor on the right side of the intake (round top)where one of its hoses goes to the EGR, and the EGR. I should also tell you that we found the main vacuum nipple (the one into the intake manifold) was off/loose so we reattached it with a tie - to keep tight. There IS vacuum at the lines (although I have never had it at the ERG but I think that is a high RPM need before I get it (?).
3) After changing the EGR and sensor (right side, not DPFE)two days ago, I reset the light with the ODPII but the check engine light came on within 10 miles (again!) - same code (again!).
4) I will drive it next to have all checks completed, hoping it will provide another clue. Failing that, and prior to taking it to a mechanic, any ideas???
Again, thanks for your time and expertise!
Don
AnswerHello and thanks for the reply...I'll try to help.
I would see if your scan tool can do an engine running test. And IF so, unhook the vacuum line from the EGR valve and put a vacuum gauge on it and run the test. You WILL get a fault code......BUT...it will also tell you IF the EGR is getting a signal from it's source.
You might find that one of the newly installed parts is defective. Remember NEW does NOT mean good.
Hope this helps,
Erik
