Check Engine Light - Code 402

[mzimmer577]

I took the groups advice and went to auto zone and had the code read for free, Thanks! It was code 402. The guy behind the counter looked in the book and all it said was the cat was performing below specification.

He said with that code the cat was ok, but was not being allowed to heat up to the right tempeture. Without doing more extensive tests, he did not know what would cause that.

Any ideas, or do I just take it in?

Thanks in advance.

 

[DonM]

Are you sure he said code 402? I just looked it up, im not seeing that code!

42 maybe?

BTW, Welcome

 

[mzimmer577]

Yes, he show me the reader and it said 402 and the book he looked in was printed from some computer file. The entries were very short and lacking detail.

For discussion's sake, let's say that it is code 42 and the 0 was some type of spacer in the display or specifically used by the maker of that particular code reader. Can you tell me what is a 42 and what does it mean?

Thx

 

[Runnin'OnEmpty]

Mzimmer, your 96 is OBD II, and the code would actually be PO402. My book says it is "EGR excessive flow detected". ???????

Codes PO420 through PO 430's indicate poor catalyst efficiency.

Does it run or idle poorly?

 

[DonM]

Sorry, I picked up the wrong book. I picked up the code book for OBD 1.


Runnin'OnEmpty is correct.

 

[mzimmer577]

It runs ok after it has warmed up and most of the time when it is cold. I do get a short period where it wants to die when it is cold and I have the A/C turned on.

I did not notice if the attempted stalling started before or after the light came on.

I get this type of engine behavior for about 2 weeks when the seasons go from Spring to Summer and then again from Fall to Winter. First time for the light to come on.

 

[DonM]

I guess that would mean your EGR vavle is stuck open? $20-$30 bucks for the part, maybe more?

I would have said the IAC at first.

 

[mzimmer577]

Is that hard to get to or is it something easy to replace like the old PVC valves? I am not a mechanical type, electronic yes, mechanic no. I do appreciate the help and at least I know what to expect now.

 

[DonM]

IMO, the PVC vavle is easyer to change. The EGR takes alittle more time to remove and replace, but it's not hard. Two or three screws is all.

You might want to use some liquid wrench on the screws first.

 

[Robb]

Often, a bad DPFE will throw the p401 and p402 codes. It goes bad more often than the EGR.

 

[TPLYNCH]

For the bad idle, clean your IAC. It's the little shiny canister thing on the drivers side of your throttle body. It controls the idle when A/C is running.

 

[Glacier991]

I'm with Robb. More often than not the EGR will be fine, and the EVR or DPFE (depending on model and year) will be the culprit, the EGR just acting out the role it's told to. You might find this thread helpful:

http://www.explorerforum.com/forums/showthread.php?s=&threadid=80692

Do some more sleuthing before you part with $75 to replace what might be a perfectly good EGR valve. If you need more info on how to test it beyond what your Haynes tells you, let me know.

Hope this helps.

Happy Exploring

CHRIS