Oldsmobile P0401 **Fixed**

[BobWiersema]

My Son has a 02 Olds Alero with a v6 and it has a P0401 code.
Thats easy, on my Ford it would be a DPFE. But this Olds doesn't have one.
The best thing I can find is it may be the MAP (Manifold Absolute Pressure) Sensor. If anyone has any experience with these GM engines or can point me toward a good forum, I would appreciate it. I need to fix this ASAP, he took it for the emission test (for some reason) and it obviously failed, well they reported that to the state and now he can not renew his plates that expire at the end of the month. I guess I shouldn't expect a 17 year old to be sneaky enough to outsmart the state by renewing the plates first.

Thanks,
Bob

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* Problem Solved. See my last post. *
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[jimmyfloyd]

good forums for that would be 60degreeV6.com, or w-body.com (even though it isn't a w-body, it's an N body, they share that motor)

With that being an EGR code, you might have a dirty EGR. I know people have cleaned them and had decent luck. Just need a new gasket (I think it's like $5-8 at Autozone) and some carb cleaner. As for the location of it, I'll have to check my girlfriend's alero (she's got an 02 with the V6 also) tonight and let you know. I did this on my bonneville to replace a similar code before.

I believe the EGR is behind the Throttle Body, near the rear driver's side of the motor.

edit: Here is a picture I found online. You can see it sticking up right behind the throttle body opening

 

[BobWiersema]

Please, Anyone, Out of time and Money!

I replaced the MAP sensor, cleared 401 code, took it for a drive and watched the system go through the normal monitor tests. It failed the EGR system and set the check engine lite back on. So, I went and bought a new EGR valve and PCV, reset the system and hit the road. EGR System test failed again and check engine lite back on.

Please help, what do I do next? Vacuum leak? Carbon block?

This is the last non-Ford I will ever have anything to do with!
I bought this car for my ex-wife and now my 17 year old son drives it for school and football.

Any ideas would be great.

Thanks,
Bob

ps. jimmyfloyd, thanks for the links, one thing I found is they talk about carbon buildup, I don't think Ford has such a problem with the EGR system
but I am thinking about using SeaFoam.

 

[BobWiersema]

Problem Solved Code P0401 Fixed

After searching around for an answer for over a week, I ran into a buddy from Allied Auto, and after several rounds of drinks he pointed me toward the Wells Engine Management web site. There I found this video explaining exactly what the problem was and exactly how to fix it. He told me this was a very common problem with the GM 60 degree engines (like the one in the picture).

The EGR port in the intake manifold plugs up, all the cleaner in the world wont remove this tar like carbon that collects at the exit just behind the throttle body. This 5 min. video explains it better then I can.

​

If you watch the video you will notice that they use the example of a 97 3.1L with over 107K on it. My Olds is a 02 3.4L with under 70K on it. The intake manifolds are slightly different. This is mine with the throttle body removed before cleaning. The arrow points to the EGR outlet port on the bottom.

The EGR Valve is also removed in this picture, it is mounted to the right of the intake. In the video the port appears to be almost straight in. On mine it has a 90 deg bend that turns up into the bottom of the manifold. This is the reason I couldn't clear it from the EGR side. If you look very close you can see a tiny opening in that pile of black goop. The opening should be about 3/8 in. That little pin hole in the carbon allowed just enough flow from when the EGR valve was open to suck in moisture from the exhaust. Without full flow the exhaust gas cools down enough to condense and cause this mess on the back side of the throttle body.

It took much longer to clean out the manifold port and clean up the throttle body then it took to take it apart and put it back together.
Once it was all cleaned up and reassembled I plugged in my laptop with PCMSCAN software, I reset the ECU and hit the road.

Error code P0401 (insufficient egr flow) did not come back.
After a while the ECU started completing emission system tests. That looks something like this with the Palmer software.

(Full Screen) (Zoom In of Status)​

The Palmer Performance software can check your emissions status before you go wait in line or have to pay for the emissions test. As you can see in the example above all systems are go. So the Oldsmobile will hit the test line on Tuesday, get the plates renewed and my son is back on the road (I don't know if that's good or bad). :

Links used in this repair:
Wells Engine Management: http://www.wellsmfgcorp.com/video_egr_hq.html
Palmer Performance Engineering: http://www.palmerperformance.com/
60DegreeV6: http://60degreev6.com/

Peace Out;
Bob

 

[BobWiersema]

Fixed

Problem solved, see above edit.