Gas Cap


My 98 Chevy Luminas service engine soon light came on soon after I got gas recently. Suspecting a leak thru the gas cap I put vaseline around the threads and the light went out. After a few weeks the light came back on and no amount of vaseline worked. I bought a new gas cap and the light went out again. A few days later the light came back on and wouldn’t go out. I put the old gas cap back on, the light went out and a few days later the same thing happened, light back on. Any suggestions would be appreciated.


This could be related to your gas cap, or it could be a myriad of other things that are causing your CEL to illuminate. Guess-work is not a good thing, so rather than relying on long-distance guesses by well-meaning members of this board, you should have the trouble codes read (free-of-charge) at an auto parts retailer such as Auto Zone.

Once you have a trouble code (the format would be something like P1234), then you can post back here for advice on a relatively firm basis, rather than relying on guesses.


That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. It likely will have a format like P1234.


I could be wrong (no kidding!) but I’m suspecting the code will refer to the canister.


Hi I went to Autozone and had the codes read. The first time it said no problems and when I started the car back up the service light was out. The next day the light came back on and I just got back from Autozone for another test. This time code P0341 came up. I tested it again and no codes showed and now the service light is out again. Thanks for your help.


My book says that P0341 definition is Camshaft Position Sensor A - Bank 1 CKT Range/Performance. CKT may be an abbreviation for Circuit as P0340 thru P0349 have the word Circuit in the trouble code definitions. I have no idea of what the trouble code means.


Can be Camshaft position sensor or Crankshaft position sensor… On a Chevy, it’s usually the camshaft position sensor.
Either of these sensors rarely fail (no moving parts). Most usual is a problem with the wires from this sensor to the wiring harness. Either it’s almost touching something and has worn through and is intermittently shorting out, or the wire is broken inside the insulation and is intermittently disconnecting. In either case it will get slowly worse until it suddenly strands you. You could wrap electrical tape around the worn insulation, or if you can find the break in the wire you could cut the broken piece out and patch it. Or you could just replace the sensor (they aren’t expensive) as it comes with the wire.
Another possibility is a bad connector (corroded or dirty) but this is not usually intermittent.
Other conditions that can trigger this code on some cars are: a bad ground on the ECM, or a bad sparkplug wire.