CEL p0440 back on after gas cap replacement

[bearandbee]

Just purchased and need to pass inspection ASAP. My lines around the EGR look OK. Anyone know what I should inspect or replace next? Many thanks!

[nocturnalVX]

My VX has that code constantly popping up, and a couple of mechanics have found nothing wrong with the evap system. The theory is that there is an electrical gremlin causing the trouble code, but I have not had time or $$$ to chase it down. I tried being sneaky and clearing the code a day before getting the VX tested, but (even though it didn't "fail") it did not successfully get through the testing... I brought the VX in to my mechanic near the testing facility, and he got it passed. However, 0440 reared it's ugly head again soon after. Good luck!

[deermagnet]

EVAP problems are a real pain. I could be so many things that it's hard to pin it down. The system detects very small leaks that could be anywhere. An Isuzu mechanic with the Tech2 scan tool is the best way to find problems.



I have an Isuzu tech video for EVAP concerns that may give you a headache when you see how this system works. The P0440 code is mentioned in the vid. I believe you need a RealPlayer to view it.


23.2 MB, 12:58 - http://www.drivehq.com/file/df.aspx/publish/mgpa/techvids/evap.rm

Mark Griffin

[bearandbee]

THANKS! I'll review the video and then check prices on a Isuzu mechanic in north Atlanta.

[bearandbee]

Dealership says it could be because I replaced with a aftermarket cap. Isuzu cap is $48. Diagnostic service is $97.....hmmm

[Triathlete]

If the code came up AFTER you replaced your cap I would say it is the aftermarket cap.

[bearandbee]

If the code came up AFTER you replaced your cap I would say it is the aftermarket cap.

No the code was on when I purchased. I replaced cap and cleared code. Then code came back at 1/2 tank, 110 miles.

[Gussie2000]

Then is not the gas cap.

Is more likely a vacuum hose leaking or electrical gremlin

[Amnesia]

I've had my VX since it had around 30,000 miles on it and I'm the 2nd owner. I got that dreaded code & CEL sometime after that... can't remember when, but must have been after 100,000 miles, since I bought an extended aftermarket warranty & would have taken it it otherwise.

So the light comes on shortly after 100,000 miles & stays on... at first it would go off on it's own, but then return. This happened a few times & then it just stayed on. I replaced the EGR once and it stayed off for a few months. Then back on. I finally just accepted it & lived with it for years...

Then this past fall I developed a REALLY high idle. At first it jumped to around 1200RPM or so, & over the course of a couple of weeks, it had progressed to around 3200-3400RPM. Bad news for winter driving, since it wanted to push me instead of letting me stop. (Also VERY harsh engagement into Drive!)

So this past winter with over 200,000 miles on the clock, I replaced the lower intake gasket to fix the vacuum leak that was giving me the HIGH idle. (2nd time I've replaced that due to vacuum leaks, but the first time I didn't have a high idle at all... if I remember right it was just running a little rough.) Anyway - I put it all back together & fire it up and to my dismay, the idle was STILL high... Although lower than it had been. It was still around 2500 or so. Crap. This is great. I revved it. I drove it. I shut it down... Next time I started it up it was a little lower... Then it was lower again. By the end of the next day, my idle had returned to normal & it was running like a champ again. I think that since it was so bad, for so long that the computer had to relearn and adjust over a few start / run cycles.

The point of my story is this. This time when I replaced the lower intake manifold, I realized that in the process of doing so, I had previously allowed the right, rear corner of the intake rest on the gasket while I was trying to re-position things; struggling with a fuel line bracket or something back there that makes this step a PITA. Anway - I think that when this happened before, that it left an indention in the gasket which still allowed a small leak, that eventually let go and developed a large leak that led to my high idle. Since replacing the gasket this past winter, my light went off & has stayed off for nearly 10,000 miles!

Also, before the idle found it's way back to normal, I did a few other things. I carb cleaned the heck out of the MAF (in the air-intake tube), as well as taking the IAC motor off carb cleaning it out thoroughly too...

Might be something worth looking into.

[nocturnalVX]

I finally got my VX free of the CEL code P0440 by having the air filter valve (part # 8-97130-368-0) replaced.

[blacksambo]

What's an air filter valve?

[nocturnalVX]

What's an air filter valve?

Some goofy solenoid thingamabob (possibly a doohickey... I'm not quite sure) that causes CEL code P0440 (EVAP system malfunction) when it goes bad.

[Ldub]

Some goofy solenoid thingamabob (possibly a doohickey... I'm not quite sure) that causes CEL code P0440 (EVAP system malfunction) when it goes bad.

Could you PLEASE get a part # for that...

[nocturnalVX]

I posted the part # if you really need it, but Merlin can let you know for sure if it is a thingamabob or a doohickey. See you soon bro!

[nocturnalVX]

Here is that thread we we talking about last night. I hope it helps getting Suzie better.

Oh, and it turns out it is not a thingamabob OR a doohickey... it's a whatzitznutz. FYI