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Ron Z.
Ron Z., - Saturn Tech -
Category: Saturn
Satisfied Customers: 17957
Experience:  18+yrs experience. State Inspector and Saturn Diagnostics
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service engine soon..engine soon light..light keeps coming..30 mins

Customer Question

my service engine soon light keeps coming on but the car is still driving 30 mins to work without a problem in engine performance
Submitted: 4 years ago.
Category: Saturn
Expert:  Ron Z. replied 4 years ago.

Welcome! I'm Ron Z! I will do my best to answer all of your questions. For easy access to this thread, bookmark it now! Please read everything!


When the Service Engine Soon light comes on, this is the on-board computer's way of telling you it sees a problem in one of the monitored systems. Unfortunately, there are literally 100's of parts and sensors monitored in various systems, and to take a "guess" as to which part/sensor in which system is faulty, is virtually impossible. However, if you are not experiencing any drivability issues such as skipping, stalling, shifting problems, etc, then more than likely, the problem is going to lie in the EVAP (emissions) system. Very commonly, this could be a faulty, loose or missing fuel cap or even putting fuel in while the vehicle is running. Check the cap for any cracks in the rubber o-ring on the underside. Check the fuel filler neck for any signs of chips or debris. Check under the vehicle, around the area of the fuel tank and the EVAP canister looking for any vacuum lines that have dry-rot cracks, holes or loose/missing connections. If these all check out, then the best thing to do at this point is to have the "p-codes" read from the on-board computer. These p-codes are what is used as a "starting point" for the diagnosis and will tell which part/sensor in which system has the fault. There isn't a Mechanic on the planet that can tell you what is wrong with the vehicle just by "looking" at the Engine Light. Every single Mechanic's first course of action WILL be to obtain the p-codes. Once you get these p-codes you can more accurately and efficiently diagnose the problem and then make the repair. You can have these p-codes read FREE (except in California) at any local "big chain" part store (ie. AutoZone, PepBoys, Advanced, etc). If you still need help after retrieving the codes, you can bring them here, and any of our Techs can walk you through the diagnostic procedure, and then even help you make the repair if you feel confident enough to try.

Customer: replied 4 years ago.
when i hooked a handheld to the vechicle it said manufactuer defect
Expert:  Ron Z. replied 4 years ago.

It says this because the scan-tool you used was generic. Just to the left of that description should have been a "p-code". If I can have this code, I can tell you what the problem is.

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