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Ask Ron Z. Your Own Question
Ron Z.
Ron Z., - Saturn Tech -
Category: Saturn
Satisfied Customers: 18553
Experience:  18+yrs experience. State Inspector and Saturn Diagnostics
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2002 SL1 just yesterday the" Service Engine Soon" light

Customer Question

hi
JA: Hello. What do you want help with?
Customer: 2002 SL1 just yesterday the " Service Engine Soon" ***** *****ght stayed on
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Saturn. The Saturn Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: see my previous post 2002 SL1 just had "Service Engine Soon" light stay on.
JA: Are you hoping to fix this yourself?
Customer: no
JA: OK! The Saturn Mechanic will help you with the diagnostics so you are sure to get this fixed right. Is there anything else important you think the Saturn Mechanic should know about your Saturn?
Customer: 2 things
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Saturn Mechanic about your situation and then connect you two.
Customer: Just had oil change 2 weeks ago only has 45800 total miles - little driven car
Submitted: 1 year ago.
Category: Saturn
Expert:  Ron Z. replied 1 year ago.

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 control/recovery) system. Very commonly, this could be a faulty, loose or missing fuel cap or even putting fuel in while the vehicle is running can set the light. Check the underside of the fuel cap for any cracks or signs of defects that may keep the cap from sealing correctly. If there are any doubts about the inspection of the cap, replace it. Keep in mind, you will need a cap that meets OE Specs. Those "universal" or "locking" fuel caps sold at after market parts stores do not meet OE specs, and will not seal the system correctly. Check the top of the fuel filler neck for any signs of damage or debris. Check under the vehicle, around the rear areas of the vehicle, 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 Diagnostic Trouble Codes (aka "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. It's standard diagnostic procedure. Once you get these p-codes you can more accurately and efficiently diagnose the problem and then make the correct 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 my answer has helped you, please help me by leaving a rating or accepting my answer so I may be credited. Rating or accepting my answer does not cost you extra. It allows me to be credited for my work. Please rate or accept. You can ask follow-up questions after you rate or accept.