Service Engine Soon

OK what’s up with my 2003 Maxima? The “Service Engine Soon” light came on & stays on even after several start-ups. Gas cap was tightened several times per manual, battery disconnected & reconnected, light still stays on. 95,500 miles on car. Owner’s manual says SES light comes on indicating potential emission control malfunction. I suppose impossible to diagnose without hooking up to dealer’s computer?

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 (like P0123) not just their translation into English and post it back here. 

Regarding warning lights:

  1. if the coolant temp light comes on, shut off the engine ASAP

  2. if the oil warning light comes on, shut off the engine ASAP

  3. if a FLASHING MIL/CEL comes on, shut off the engine ASAP

    ASAP means driving to the berm of the highway right now and not waiting for the next exit.

But if the MIL/CEL is not flashing, then it’s not an urgent indicator.

Yes, you need to have it hooked up to a code reader to find out what the code is. Many auto parts chains will read these for free - i.e. you do not need a dealer. Call around to parts chain stores, ask if they read OBD-2 codes as a service. Have them read, and post the actual codes (something like, e.g. P0123) back up here.

The CODE that you get, when the auto parts store scans for the cause of the ‘service engine soon’ light, can help a LOT in finding out what is wrong with your car.
Also, tell us how the engine is running, and if you have done any maintenance on the engine, or transmission, in the last year, or two.
All information, about the car, can be useful in finding out what is wrong.

You can read the code yourself if you have a reader…OR take it to a independent garage or national chain to have it read. Anyone with a ODB-II scanner can read the codes. You need to have the codes read before you can go any further.

Thanks for the info. I didn’t know some auto parts stores did it for free. I’ll give a call & see if the ones around here do it. I did just change my oil, rountine maintenance I’ve always done on the car. Coincidental the SES came on shortly after this recent oil change? Car seems to run normally, no missing or stalling at all.
Thanks for your helpful answers.