Cel P0402

[sammm]

I got the dreaded P0402 check-engine code again. I cleaned the intake and throttle-body thoroughly last year (around this time) and it's come back again. There's a ton of posts about that code on the board. Has anyone else (with an NB) seen this code and have it return on a regular basis? Seems to be a common issue with '99-'00 models.

Here's the supposed solution - LINKIE

[jolberry]

That sucks if this a common reaccuring problem.
Maybe I need to clean my intake and throttle-body soon before I get this code.

[POS Racing]

Why would it wait almost a year to reappear??? You making your own gasoline?

How many miles have you put on it since last time you cleaned it....

[altiain]

I've cleaned my upper intake manifold and throttle body the old-fashioned way once, about 2 years ago. I've never seafoamed my car. 105k miles (50k in the last 3 years), and I've never thrown that code.

Makes me wonder... sift through the old threads and compare the inside of your head to mine. Yours definitely had a lot more oil residue than mine. I wonder if dino oil blowby could have gunked something up somewhere?

[sammm]

How many miles have you put on it since last time you cleaned it....

Can't be more than 5-6K in the past year. From what I've read, it could come back after 100 or 10,000 miles.

I wonder if dino oil blowby could have gunked something up somewhere?

Good point. Now that I'm running synth, it could have cleaned out some old dino trash.

[trackdog]

Some cars seem to have a high level of oil fume bypass. This could be from the PCV valve and or weakening in the engine components such as the rings. Now don't get worried your engine is about to blow, just there is more bypass and that is not going to cause any catastrophic failure. The pressure in your crankcase can get pretty high and the return hose from your valve cover over to the intake can show a trail if you look closely.

Using Seafoam (Horsepower-in-a-can) can sometimes set this code off. This is not the fault of the Seafoam, just the cleaning of the EGR pipe as it returns back into the intake manifold. I personally use Seafoam at least 3 times a year. Its cleaning agent removes a ton of carbon build up, which robs you of horsepower and fuel mileage. If you get a Code after Seafoam, run another can through. Also consider putting a can in your gas tank for injector cleaner.

We sell a ton of this all over the country, plus it kills all the bugs in the neighborhood! If you want to use the Seafoam and do not know how to use it, let us know and we can repost a Step-by-Step.

Gary

[sammm]

Using Seafoam (Horsepower-in-a-can) can sometimes set this code off.

That's one thing I haven't done yet to this car is Seafoam it. Should I use a whole can in the intake and another in the gas tank? Should I fill the gas tank up after I dump the can in? Change the oil after xxx miles? Thanks Gary!

[Titus]

I would be interested in a seafoam GTG.... Anyone got a good place? The last time I seafoamed it was in my driveway and I ended up with 3 different neighbors in my yard to find out what i had did with one starting to dial 911 thinking there was a fire. I got less than half the can through and stopped to calm the onlookers.

[POS Racing]

let us know and we can repost a Step-by-Step.

Gary

Yes please! I'd be interested in learning the Trackdog method of Seafoam! :afro:

[Billy Blaze]

I just did the fuel tank and crank case with the seafoam, the ratio's are on the can...doing both took two cans.
I used the spray seafoam on the throttle Body, all the treatments seemed to work great.
Hope that cures the problem.

[MadMerv]

If you ever opened up the intake, you would see why this happens! They just run WAY to rich and carbon builds up everywhere. The 99 that used to reside at Granbury started it at 80K miles and did it on and off 'till it went to live elsewhere.

Listen to Gary...SEAFOAM!

[sammm]

The plot thickens....the past few mornings on my way to work I noticed the car was taking forever to come up to normal temp. I just pulled the t-stat and sure enough it was stuck open. Since the car was slow to come up to temp, could that have made it run extra rich for extra long and contribute to the EGR code?

I had a spare OEM t-stat and put it in. I think I bought it right after I bought the car, but never got around to installing it. I did get a couple cans of Seafoam and just got done fogging the neighborhood for the first time.

[sammm]

Success! After replacing the t-stat and seafoaming the intake, the CEL went off on it's own today! I still think the t-stat failure contributed to throwing the EGR code.

[POS Racing]

Sweet!

[channelmaniac]

Great news!!!

[sammm]

Bringing this one back from the dead. In the past few weeks the P0402 has come back twice. CEL went off on its own, stayed off for a few days and came back again. The idle has been dropping more than usual as well lately. I may crack open the intake again and take a look at it.

I found this on the pointy board...seems flakey to me, but I may give it a shot.
http://www.asashop.org/autoinc/june2006/techtips.htm

[MiataMike]

Bringing this one back from the dead. In the past few weeks the P0402 has come back twice. CEL went off on its own, stayed off for a few days and came back again. The idle has been dropping more than usual as well lately. I may crack open the intake again and take a look at it.

I found this on the pointy board...seems flakey to me, but I may give it a shot.
http://www.asashop.org/autoinc/june2006/techtips.htm

Cursed P0402!!

I had my 'bout with mine. But now I know why mine is on. (no )

[cone-cerned]

Give it a try, what can you lose? TCB pricing and reversible.

[POS Racing]

Give it a try, what can you lose? TCB pricing and reversible.

+1!

Heck give it another Sea-foam treatment while your at it!

[randy7601]

Makes me wonder... sift through the old threads and compare the inside of your head to mine. Yours definitely had a lot more oil residue than mine. I wonder if dino oil blowby could have gunked something up somewhere?

Talkin' about jeff_man?