Check engine light (little yellow engine icon) came on last Wednesday on my 08 4WD with about 5000 miles. I was on the way to park the vehicle before heading to the airport. It sat for a week. Got back last night and drove home and it's still on. Runs & drives totally normal.

Is there a way to see what code(s) got set? Any magic secret voodoo technique? Or should I just drop it at the dealer?

 

If you have a Scanguage you might be able to read it.. you might not, I have one and a check engine light I had didn't register a code for it but there was one when read at the shop.

Unless you forgot to tighten your gas cap last time you filled up, you definitely want to get the thing checked out.... check engine lights can be an early indication of a problem or not important at all. A misfire or two I've been told is usually okay. However mine turned out to be the motor for a baffle on the HV battery cooling system. That battery costs thousands to replace (though it would have been on warranty). I'd like to keep its cooling system running.

Loose gas caps are frequent causes of Check engine lights many cars. If its the gas cap, put it on tight (so it clicks) and it will clear after a few starts.

You should only be charged one hours labor or less and most dealers will reduce your repair bill by the same amount if you have it repaired there. Also since you are still on warranty is should be completely free for you.

 

Thanks! The gas cap is definitely the 1st thing to check.

The 2008 (and maybe earlier models, not sure) has a special light for a loose/missing gas cap. It's the "check fuel cap" light. I'm glad they decided to do this as it probably saves many unnecessary dealer visits and owner frustrations/embarrassments.

I wonder how many dealer visits on any given day are gas cap errors. I'll bet it's a lot.

 

We get at least one a week at my shop, we scan it and if it is a p0420 or 440 code we check the gas cap and if its loose we n/c the customer and clear the code.

 

They called and said it's the evap system, probably a leak. Similar to a loose gas cap, but they have to find it. Service advisor said they do a pressurization thing with a dye and let it sit overnight. Apparently the hope is that the leak will be marked with dye in the morning.

 

What most shops use a "smoke machine" This is a smoke generator that pressurizes (1.5 psi) the gas tank and evap system with nitorgen and a "smoke". This is what I use to find evap leaks.

The PCM does a test when conditions are meet to seal the gas tank and hoses and induce a slight vacuum, hold it and count how fast it reduces. These will detect and set a light if a hole is as small as .020"

 

Wow, smoke and mirrors. Literally!!

Well, the advisor dude called. The smoke/mirror test showed the filler neck has a leak. Not sure if it's a faulty part or what, but he said it's not something you can repair. I was thinking bubble gum or maybe duct tape but he said 'no', it's an assembly and needs to be replaced. They already ordered the part and it's being delivered today.

It's times like this I'm glad I live in the same city where a regional parts depot is located.

He said they should have it done tomorrow.