Some of these warning appear as certain TIME limits are reached automatically, and others sinal a problem with engine or trans sensors. Have your IDLE AIR CONTROL VALVE cleaned up or replaced and clean the THROTTLE BODY as well! Chances are that your O2 sensors are clogged up with burned COOLANT from DEXCOOL on them! I NEVER USE DEXCOOL in.ANY GM engine any more! I use BENZ or AUDI coolants instead because it will protect the GM gaskets from breaking down! It took hose idiots at GM engineering nearly TWENTY YEARS to figure out that DEXCOOL was ruing their engines! WHAT A SHAME and a scam on the overall public! Nearly all GM engine made from 1996-2004 were seriously affected by this fiasco! BE SURE that you run GUMOUT through your PCV VALVE for several minutes as this will help to remove any GM COOLANT that is baking into the workings of the GM )2 sensors! GOOD LUCK!!

Hi when you first start the car the system does a check so the light comes on and should go off. if it does not something else is wrong given that this is a 14 year old car what do you expect. when cars get older than 8 years old they start to become a money pit as everything is so worn out.

The PCM has detected a fault. If it continues to detect the fault, it will continue to illuminate the SES light. If the fault goes away, it will shut off the light. You will need to get the computer scanned to find out what system/circuit is causing the grief. Then a diagnostic must be done to find out what's wrong.

It's coming on for a reason. If there really is no code that comes up, then it's a problem with the diagnostic portion of the computer.

If the light is on, there's a code stored. Auto parts scan tools will only read powertrain P codes. But there are body B, chassis C, and data U codes also. You need a high end scan tool to read those.

You says the SES light is on and there are no codes . . . your scan tool reads only P0xxx generic codes which are worthless at best, try reading with a scan tool that reads P1xxx OBD-2 DTCs (manufacturer specific)

Due to a small coolant/oil leak, I had my 2000 Grand Am GT's head gaskets replaced. That was a week ago. And after I have been driving it around since then, my "Service Engine Soon" light has kicked on, and stays on. I have had codes ran on it, but nothing pops up. And I have had the light cleared a few times now. But every time I start the car up, the light comes back on. What could it possibly be?