Check Engine Light

You need to pull codes to find out why the light is coming on.

Odds suggest a problem with the cap not being properly secured, but pulling codes would tell you. If the cap makes a ratchet noise (clicks) when you tighten it all of the way, then turn some more, then you should have a habit of turning the cap so that it clicks at least three times. If you do not make the cap click, then it might not be tight, and the resulting leak would trigger a code.

Thanks Jeff, but believe me when I say the cap is secure and the inner seal is in great shape.

Then you need to pull codes to find out why the light is coming on.

Lots of places pull codes for free. AutoZone formerly allowed you to use their code reader, but I'm not sure if they still do this. It's worth it to ask them. In some places, AutoZone employees would actually pull the codes for you, nothing is easier than that. If you have to use the scan tool and pull codes yourself, it is very easy.

There is a plug along the bottom of the dash board in the area where the clutch pedal would be if you had a clutch -- even if you don't have a clutch, the connector is in the same place. You plug the scan tool in, turn the ignition to ON, but not START, and wait for the scan tool to list up the codes.

The Evaporative Emissions Control System (the system affected by the gas cap) will list a code in the range of P0440 thru P0456. Some of these codes are electrical failures of solenoids and valves, but most of them describe physical leaks.

If you can't find a place that pulls codes for free, for the cost of pulling codes twice, you can buy a very nice scan tool that can be used on any '96 or later car or truck -- you can pull codes for a neighbor or relative some day. I bought a scan tool for $120, but you can find them for about $90. I found mine at an auto parts store, but you can get a very good unit brand new on eBay and probably save a few dollars if you can wait for UPS to show up at your house. I've seen them at Costco, and WalMart carries some.

And when you put the scan tool on it, what DTCs did you get?

He didn't put the scan tool on. He assumes that since the light comes on after getting gas, then that must be the problem so he replaced the gas cap twice, and disconnects the battery to clear the code.

I know, it was a hint that he needed to do it!

Nothing beats shotgun replacement of parts, twice no less, without even the slightest clue as to what's really wrong.

If disconnecting the battery clears the code, perhaps having it connected is the problem. I think that by leaving it disconnected that should clear up any issues with the check engine light coming on. :)

- Chris

Just a guess here, but me thinks the ripple affect would be an even bigger problem than a pesky light. Just a thought ...

Well, there is that "only approved automotive use for black electrical tape" technique...

Good response! Clean and deadly!

RYFM has been replaced by CYFC!

Ha!

H.