General Question

Heather13's avatar

Any idea what could make my engine light go and come back on?

Asked by Heather13 (495points) January 4th, 2017

I have a 2008 VW Jetta GLI. Its in pretty good condition. I just bout it in November, second owner. Its running smoothly. Anyway, about a month after I drove it, it started to not turn over right after fueling it. I would have to wait 5 to 10 minutes before the engine would start. This is around the time I noticed the engine light stayed on. This happened for 4 to 5 times in a row. I took it to Advance Auto to get a diagnostic test. It only showed a code for the gas cap. Even after tightening it, the engine light was still on. Eventually I decided to get them to test it again. This time the only code came up was fuel pump. I decided to see if it would help to put a fuel injector treatment in it. After a few days, the engine light went off, and I was able to start the car right after fueling without waiting. Now today, I am driving down the road and saw the engine light coming back on. And it won’t go off. I tried tighting the gas cap, etc. And its still on. Any ideas or experience?

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14 Answers

chyna's avatar

My Honda will do that if I don’t tighten and then click the gas cap at least 3 times after fueling.
I would take it to a Volkswagen dealership and let them diagnose it. If you need a fuel pump you don’t want to be stranded somewhere and have the expense of having your car towed.
Maybe one of the more mechanical people on here will have more information.

ARE_you_kidding_me's avatar

It’s a VW. I’m not being sarcastic, they have horribly designed electrical systems but it could be anything. I diagnosed something like this using an elm and a logging app.

LuckyGuy's avatar

understand that fixing the problem will not turn off the light immediately. Depending upon the year, make and model It might take 10 or so full driving cycles of correct operation before the light will turn off on its own.
You need to use the tester that Advance Auto offers for free (a great service by the way) to read the code. After you write it down check to see if there are any codes “Pending” and write those down. Then clear the codes. That will turn the light off immediately.

CWOTUS's avatar

Further to @LuckyGuy‘s good advice, if there really is a continuing problem then “clearing the codes” as he suggests will only clear what is currently stored in the system’s cache of “current problems”. The code will still be generated as it should be if there really is a problem.

In addition to all of the foregoing: Do you know what the vehicle’s maintenance schedule is? My “Maintenance Required” light comes on at least once per year when it doesn’t need to, as the computer is set to remind me for 5000-mile oil change intervals. Since I use synthetic oil and only change at 10,000-mile intervals (or annually), then I get at least one “false” warning per year, which I simply clear and ignore.

Heather13's avatar


I am not sure.
I only had it for a couple months. I don’t have the manual.

Idk what to do ar all.

Heather13's avatar


Can you explain it a little simpler? Like I said, Advance auto did the diagn test. Gas cap code on first test, and fuel pump code in the second.

The light dud go off for several days after I used a fuel injector cleaner. But today, it came back.

kritiper's avatar

Replace the fuel cap with a new one to eliminate it as a possible source. (Or find someone who also has a car like yours who is not having a problem and switch caps for a while.)
Do not overfill the fuel tank! When the nozzle shuts off the first time, stop fueling!
I doubt the problem is your fuel pump because when they quit, THEY QUIT!
Like @LuckyGuy said, when they check the codes, write them down. I have a book listing code faults for some cars, generic, not specific VW codes.
When I had a problem with my Nissan, the first thing we checked was the cap but the problem was the charcoal canister that captures excess fuel vapors from the tank. If you overfill the tank, you destroy it.

kritiper's avatar

Let me know what you find out.

Nostromo's avatar

Sounds like the fuel pump is bad OR the filter is clogged. The latter’s a cheap fix. The former not so much.

MollyMcGuire's avatar

Have diagnostics run. If nothing shows up ignore the light. That’s what they told me to do and I did for four years. Then I sold the car. ABS burned for a few years in another car. I ignored it. Dealership service said disk brakes were fine but the ABS not working. I was thrilled with that and never thought about it another minute. Still driving that car. I don’t like ABS.

jca's avatar

Here in NYS, I’ve been told that the car won’t pass inspection with the service the engine light on.

kritiper's avatar

Sometimes, when a momentary problem occurs, the light will blink on and go back off to indicate that there was a momentary issue. If the issue pops up again the OBD2 may log a complaint in the system and turn the light on that then stays on.
(OBD2 = On Board Diagnostics, 2nd generation. 1st generation (OBD1) didn’t have a “Check Engine” light, but did have a computer with a blinking light on the computer itself to indicate issues noted.)

kritiper's avatar

Like @jca noted, as in Idaho. If light is on, vehicle will not pass (emissions) inspection.

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