Why does my service engine light keep going on and off?

Question

On monday my service engine light came on about 50 miles after I filled up. I went to a quick lube center to get my belt changed and the tech checked the codes but said I needed to take my car to a GM dealership because they didn't have the codes in their system. He said that it wasn't anything specific and turned the light off for me. Well, on wednesday after i filled my car the light came on again, a while later while driving in town the light went off and then this morning it came on again after an 80 mile drive. Why is it doing this? It is a 1999 Oldsmobile alero 2 door v6

Answer 1

you car has a pressure sensor that goes in the gas tank ,,you almost answered your own question there,it only does it when you seem to add gas to it,,you need to make sure that your getting the gas cap back on real tight ,all its telling you is its loosing pressure from the tank,make sure the cap is on tight,,and make sure that cap is in good shape,,it may be a bad gas cap causing this to happen,its not a serious thing though,,if you get a cap and it don't help it,,then take it,by any auto zone store and have them scan it,,its free,and they can tell you exactly whats causing it to come on,,and they will also have the part to repair it with,,good luck,hope this help,s,,have a good x-mas.

Answer 2

Without the code I can only guess.

But you say the light came on after you filled the tank. Sounds like a loose or bad gas cap. This will trigger the EVAP codes.

To reduce hydrocarbons in the air modern fuel systems pressurize the fuel tank. They will also feed the fumes into the engine to burn off the hydrocarbons from the fuel vapors. If the cap is loose or defective the system cannot build the required pressure and triggers the "Check engine" or "Service" light.

If Quick Lube told you the code number you can do a search on the internet for ECU or Trouble codes for Oldsmobile and I bet you have an EVAP code.

Answer 3

I'm gonna take a stab in the dark here, and ask if your leaving the car running while you fill your car up? If you are, try leaving it off the next time and see if the light comes on. If it does, then you have a bad gas cap. If not, then you need to start leaving you care off while pumping gas. Also, it's dangerous to pump fuel while the engine is running. What happens is that when the fuel tank is near empty, it's full of fuel vapor which is the part of fuel that actually catches fire. All it needs is a spark from the fuel pump to ignite the vapor and then....... well your not gonna have a good day after that!
Hope this helps!

Answer 4

Many cars nowadays have 2 lights. One is the service engine light and the other is MIL(Malfunction indicator light, or check engine light). The service engine light illuminates to remind you when normal engine service is due, oil changes, etc, depending on mileage. The check engine (MIL) comes on when you have something wrong with your engine that needs to be repaired. As long as the condition exists, the light will stay on and not go off until repairs are made and the MIL reset.
Your owner's manual should tell you how to reset the service light after servicing. If you don't have the manual, call the dealer, because each vehicle has a different way to reset the light. Autozone will put a code reader on your car to read the malfunctions and advise what needs to be done to repair.

Answer 5

This motor vehicle may be geared up with a easy motive force module, a small circuit board enclosed in a small plastic housing taped to the harness in the back of the glove container. the sunshine motive force module must be failing. additionally whilst between the solenoids that actuate a working laptop or laptop controlled gadget at the same time with Exhaust gas Recirculation, Evaporative purge administration or the transmission torque converter seize (TCC) will become shorted the intense modern pass in the process the ECM (on-board laptop) can injury the ECM, if so the sunshine ought to "flicker" and the ECM might ought to get replaced. The provider Engine quickly easy ought to in no way "flicker" it quite is the two ON or OFF. Flickering ought to show an inner failure of the ECM. yet another state of affairs I even have considered is a cord chafing on the exhaust manifold or an engine bracket inflicting the sunshine to flicker yet frequently that should finally blow a fuse. Early "G" physique (formally A bodies) automobiles more advantageous water leaks around the windshield that should enable water to trip down the "A" pillar into the ECM. If the windshield has been replaced there must be a threat of a foul sealing job at the same time with a area of interest interior the sealer fabric.

Answer 6

It could be one of many things. When you drive your car the computor is constantly checking many things with sensors placed in various systems of your vehicle. The lube center guy probably didn't have the needed type of scanner to check your car, a GM dealer will, but, you could also try an Autozone store. they advertise free engine light checks.

Answer 7

what the mechanic did was illegal.under federal law, mechanic must NOT turn off the light until the repair is done.when the light come on and off,there is a problem with your vehicle.a scan tool will shown a code and then a technician will diagnos what cause the computer to trigger code

Answer 8

you need to make sure when you put the gas cap back on that you let it click 2 or 3 times to make sure it is sealed or replace the cap with a new proper one
otherwise something is setting a soft fault that is coming and going

Answer 9

Mine does the same thing----Air gets into your fuel line---Next time you fill up put a pencil next to the hose to let air out as the fuel fills up the tank---- Tighten gas cap properly--
The light will go off.

Answer 10

More than likely either your O2 censor is going bad, or the thing that controlls it is shorting it out and needs to be replaced. Go have it checked. Mine is doing the same thing and this is what the dealership told me.