Another P0401 Question

[tomc]

I have a P0401 code that won't seem to go away.

2000 GTP, 94K Miles, No Mods. Car is running as good now as it ever has except for the SES light.

I have searched numerous internet postings and have tried a lot of the things that has been recommended. The following have been fixed / replace / cleaned so far: New EGR Valve, New MAP Sensor, New PCV Valve, Cleaned hose from EGR to intake manifold, cleaned throttle body, new O2 Sensor and repaired leak in exhaust. The repair shop has done some preliminary diagnostics and found that the EGR is functioning. They want it back to do a deeper diagnosis. Does anyone have any further suggestions before I take it in. I have heard that it may require a re-flash in order to get rid of the SES light.

 

[tomc]

A quick follow up. The EGR valve was purchased off e-bay pretty cheap (around 30 bucks). I have a feeling the pintle may not be opening sufficiently to allow for exhaust gas flow. The mechanic said it was operating but was it fully opening? Will a good scan tell this?

 

[tomc]

The one thing I haven't done was to remove the intake tube (Exhaust manifold to EGR Valve). Anyone had any experience with this? Does this tube even get clogged? How big of a job is this?

 

[tomc]

No replies on this and emissions test is approaching soon. Still doing research and I might be onto something. I had the exhaust system recently repaired but the car still sounds bad. If the lower EGR tube is leaking it WOULD make a lot of noise and probably set off the P0401 code. Maybe I have solved my own problem. Gonna dig in to it this weekend.

 

[tomc]

Had the car in for a scan this weekend. The tech told me it was the supercharger bypass actuator that would not hold a vacuum and they wanted a mere 250.00 bucks just for the part. I paid them for the diagnosis and ordered the part for 59.00 bucks. To be continued.....

 

[tomc]

The By pass Actuator was changed along with the vacuum lines in and out. After clearing the codes, the SES light came back on within 15 minutes. Very frustrating. It's going back in next week to get the computer re-flashed.

I'm still not exactly clear on what this will do. Does the tech change the parameters of the EGR flow? If not, the same data will be going back in. This seems like it won't solve anything. I hear there is an obscure technical service bulletin out there for this problem. Does anyone know the number? I would like to reference it when I take the car back in. 8 days and counting till final emissions test.

 

[Scottydoggs]

last ditch effort, get a tuned pcm with the egr codes deleted. inspection cant tell.

 

[tomc]

Found this on another website. Anyone know if this will work for a P0401 code:

If the P1404 is a false code meaning that the valve pintle is not stuck open, then new 'Valve Closed Signal' can be re-learned by the computer using the old valve.

For fixing this problem the tool you need to have is a simple OBD II code scanner that can be used to erase trouble codes.

The fix goes like this:

1. Disconnect the wire harness from the EGR valve.

2. Turn key ON and erase the trouble code(s) from the car's computer AND TURN KEY OFF IMMEDIATELY WHEN THE SCANNER SAYS CODES HAVE BEEN ERASED. DO NOT TURN KEY ON BEFORE YOU RE-CONNECT EGR WIRE HARNESS.

3. Re-connect EGR wire harness and your problem should be fixed.

 

[tomc]

This has finally been resolved. After the reflash, the light was still on so the shop started doing further tests. Turns out the cheap Chinese EGR valve was the culprit all along. I had suspected this cheap POS all along but the shop assured me that it was working. Turns out the pintle in the cheap EGR valve does not respond quick enough and it sends a signal to the computer to throw the code. Got a new one from Carquest last night, installed it and all is good. Save yourself a headache and don't buy a cheap valve off the internet.

Off to the next project.