P0401 on '99 3.8

[motitutty]

Hi folks,

I am getting the P0401 code from the PCM. I just crossed the 87K marker today. I read on other threads that the light might come on when I change the PCV valve and the O-ring issue. But I had no problem with that, I hope

Does anyone know where could I find the EGR valve? I know its usually by the manifold, but with these newer cars never know. Detailed location please.


Thanks,

-M

[BNaylor]

Originally Posted by motitutty

Hi folks,

I am getting the P0401 code from the PCM. I just crossed the 87K marker today. I read on other threads that the light might come on when I change the PCV valve and the O-ring issue. But I had no problem with that, I hope

Does anyone know where could I find the EGR valve? I know its usually by the manifold, but with these newer cars never know. Detailed location please.


Thanks,

-M

P0401 is EGR Flow Insufficient. The EGR valve on a Series II 3800 is located on the back side of the driver's side of the engine by the throttle body and upper intake manfold (UIM). The electrical connector is located at the top. There are two 13mm nuts holding the flange.

[motitutty]

Originally Posted by bnaylor3400

P0401 is EGR Flow Insufficient. The EGR valve on a Series II 3800 is located on the back side of the driver's side of the engine by the throttle body and upper intake manfold (UIM). The electrical connector is located at the top. There are two 13mm nuts holding the flange.

How do you clean a EGR valve properly? I tried with WD-40 to remove any carbon particles from the chamber, but didn't help much.

Thanks,

-M

[Saydee]

Motitutty, it sounds like we are having the exact same issue. I, as well, took it apart and sprayed it with WD-40 (plus shot some compressed air down the tubes) and have had no luck. I stopped by the auto parts store last evening to order a new EGR valve, but the guy said I should check for a vacuum leak. I didn't think these had a vacuum?? The cars inspection is due by the end of the month. So I think I'm just going to go ahead and order the part later today anyhow. Though it's a $150 gamble...

I'll let you know how it goes.

[Saydee]

Now that I recall... the Service Engine Soon light was on intermittently and a P0401 code was pulled. I replaced the PCV valve and now the light is on constantly. Perhaps I knocked something loose when I was replacing the PCV valve as well???

[motitutty]

Originally Posted by Saydee

Now that I recall... the Service Engine Soon light was on intermittently and a P0401 code was pulled. I replaced the PCV valve and now the light is on constantly. Perhaps I knocked something loose when I was replacing the PCV valve as well???

Hmm... I also replaced my PCV few weeks ago. I'll check if the same thing happen to me.

Thanks,

-M

[Saydee]

The PCV valve cover has two long spindly plastic support "tabs", one on each side (a total of four tabs).

See this diagram if you need help visualizing http://autorepair.about.com/library/faqs/bl958e.htm , it's the blue part (#2), although the diagram has the tabs much shorter than they actually are, and there are two tabs per side, not just one per side as the diagram shows.

In the process of removing the MAP sensor module I busted one of the four tabs. The MAP sensor seems to sit on it fine still. Would that be enough to cause a leak? And if so, would that give a P0401 EGR Flow Insufficient code? That's the only code I get.

[BNaylor]

Originally Posted by Saydee

The PCV valve cover has two long spindly plastic support "tabs", one on each side (a total of four tabs).

See this diagram if you need help visualizing http://autorepair.about.com/library/faqs/bl958e.htm , it's the blue part (#2), although the diagram has the tabs much shorter than they actually are, and there are two tabs per side, not just one per side as the diagram shows.

In the process of removing the MAP sensor module I busted one of the four tabs. The MAP sensor seems to sit on it fine still. Would that be enough to cause a leak? And if so, would that give a P0401 EGR Flow Insufficient code? That's the only code I get.

Here's a link to better procedure and pics for a PCV valve on a Series II 3800 engine.

http://macgp.clubgp.com/howto/engine/pcv/gt/pcv.html

GM has a PCV valve repair kit which contains both o - rings, the spring and plastic piece with the retainers for the MAP sensor. Cost around $13 - $19.

I had one of those tabs broken towards the UIM side for about 2 months and never got a EGR failure code as a result.

[Saydee]

bnaylor3400, thanks for the link! In that link I noticed the step where he removes the o-ring from the PCV valve itself. When I researched before changing the PCV valve people said to save the o-ring...but I thought they meant the orange colored o-ring that sits in the PCV valve holder, not the second black one on the PCV valve itself! I never even noticed it. So searching through the trash I found the old PCV valve and lo and behold there was an o-ring on the old PCV valve. Hopefully this will fix the issue.

motitutty, did you pull the o-ring off the old PCV valve?

[BNaylor]

Originally Posted by Saydee

bnaylor3400, thanks for the link! In that link I noticed the step where he removes the o-ring from the PCV valve itself. When I researched before changing the PCV valve people said to save the o-ring...but I thought they meant the orange colored o-ring that sits in the PCV valve holder, not the second black one on the PCV valve itself! I never even noticed it. So searching through the trash I found the old PCV valve and lo and behold there was an o-ring on the old PCV valve. Hopefully this will fix the issue.

motitutty, did you pull the o-ring off the old PCV valve?

No problem and you're welcome. Hopefully you get it resolved.

Here's some interesting info concerning the parameters for odb-ii DTC error code P0401 to set and how the PCV valve and MAP sensor inter-react or could affect the test.

The PCM tests the EGR valve by momentarily commanding the valve on while simultaneously monitoring manifold absolute pressure (MAP). The PCM will set P0401 and trigger the SES/CEL Mil light if an expected increase is not seen under certain conditions during deceleration over 9 - 12 periods of deceleration. In a nutshell: the EGR flow test occurs during gradual deceleration, a closed throttle condition and with a vehicle speed greater than 25 mph.

BTW - After you correct the problem, it may take a few drive cycles to get rid of the error code and SES/CEL light. Or you can use a scanner to reset. Good luck!

[Saydee]

Thanks for the information! The car goes in for inspection (NY emissions) tomorrow. Hopefully it'll turn out ok. Perhaps I should stop by the local auto parts store and borrow the OBDII scanner to clear the code, just to be sure it's gone.

[motitutty]

Originally Posted by Saydee

bnaylor3400, thanks for the link! In that link I noticed the step where he removes the o-ring from the PCV valve itself. When I researched before changing the PCV valve people said to save the o-ring...but I thought they meant the orange colored o-ring that sits in the PCV valve holder, not the second black one on the PCV valve itself! I never even noticed it. So searching through the trash I found the old PCV valve and lo and behold there was an o-ring on the old PCV valve. Hopefully this will fix the issue.

motitutty, did you pull the o-ring off the old PCV valve?

I dont think I did ;(...

[maxwedge]

Don't clear the code you will kill the emissions monitors and fail NYS insp. common error here, I do these every day in NY as an emissions inspector. If you clear the code with a scanner it will take a specific drive cylce to reset the monitors, this can take a variety of driving conditions to achieve.

[BNaylor]

Originally Posted by maxwedge

Don't clear the code you will kill the emissions monitors and fail NYS insp. common error here, I do these every day in NY as an emissions inspector. If you clear the code with a scanner it will take a specific drive cylce to reset the monitors, this can take a variety of driving conditions to achieve.

Awfully lax emissions control laws in NY. P0401 sets a SES light/CEL MIL light. In Texas, the first step of the emissions inspection is for the tester to check the SES light to see if on. If on you fail, period.

IMO - He's better off delaying or postphoning the test until the odb-ii system reports an IM (emissions ready) status. Before taking any of my cars in for inspection I run IM status with my trusty Actron CP9145 scanner.

[maxwedge]

BNaylor, same deal here, We fail the cars if the lite is on, or just tell the customer don't go forward with the inspection, see lots of people disconnect the battery and try and sneak thru, we know what happens now.