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Service Engine Soon light causes?


M U Tiger

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We are getting an intermittant "Service Engine Soon" light on our 1994 Olds Cutlass Supreme convertible. I just replaced the water pump (a difficult job even though the water pump is sitting near the top of the engine) and it was losing coolant, but that problem has been solved.

I've read two different pieces of advice regarding the causes for the "Service Engine Soon" light. One said to use a paper clip to short terminals A and B and the light will flash the error code numbers after flashing 12. The other said the codes can only be read by a GM Service Shop.

If the first advice is correct, where can the explanation of the numerical codes be found? If the second is correct, what kind of reader do the GM Technicians use to read the codes?

Thanks,

Jim

Webster Groves, MO

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The paperclip trick ONLY works on vehicles equipped with OBDI. Being a 1994 GM, your car is most likely equipped with OBD1.5, which you need to take to a shop to be read or get a scanner/ALDL cable. OBD1.5 codes can be read by local auto parts stores often for free if they are equipped, my local PepBoys can do this. Have you noticed any patterns as to when the SES light comes on? What speed are you traveling, accelerating, decelerating? I only ask because a common problem on these cars is for the EGR passage to become clogged, setting a code for an insufficient flow detected. This code is set when the EGR test cycle is activated, above 45 mph and commonly when decelerating or coasting.

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Thanks for the response. There doesn't seem to be a pattern to the "Service Engine Soon" light coming on. It will sometimes come on at low speed then go off; other times it will come on and stay on until the car is parked. We haven't driven it for any long period of time since I just put the replacement water pump in -- just 10 to 15 minutes so far.

We don't have Pep Boys close, so I'll try Advance Auto Parts to see if they can read the code.

Jim

Webster Groves, MO

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The main problem with the water pump replacement is that there is very little room to work in the area where the water pump is located by the right fender. It's necessary to take the right chassis stiffener bar, the expansion tank and the electronic box out (or loosened) before gaining access to the water pump pulley. The old bolts, that may not have been turned since the car was built, require some room to swing a wrench to break them loose and there just isn't much room.

Back to the original post, we still have an intermittant "Service Engine Soon" light and I will take the Cutty to our local Advance Auto Parts store to see if they have a code reader compatible with the OBD1.5 system in the Cutty.

Jim

Webster Groves, MO

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