"Service engine soon" light, car experts' help plz

[ThreeLeggedGnome]

Yesterday my light came on while I was on highway and the engine while still running smoothly was running louder than normal. It was really late so I couldn't look under the hook.
This morning when I went to church I noticed that even in parking gear my RPM was hoovering around 2k and my car would speed up on its own even when I didnt step on the gas panel. Also, putting it in reverse shudders the car momentarily. You guys have any suggestions what might be wrong with it, and also a ballpark figure of the cost fixing it?
I suspect it's the transmission but am not really sure. BTW, it's a 94 Cutlass supreme thats been running fairly reliably up to this point (98k miles).
Thanks guys.

 

[minendo]

Go to the dealership and have them run the diagnostic test. Service engine soon light can mean hundreds of things.

 

[Nyical]

Originally posted by: minendo
Go to the dealership and have them run the diagnostic test. Service engine soon light can mean hundreds of things.

What he said, it could be any number of things but by what you describe it is sounding like the TP sensor (Throttle position sensor) can cause that but to be on the safe side just take it in.

 

[XZeroII]

Go to autozone and they'll tell you what's wrong. Could be your idle sensor (or whatever it's called)

 

[rutchtkim]

i always get that with my cars. even new ones. i just ignore them.

 

[Pshawn5]

Originally posted by: XZeroII
Go to autozone and they'll tell you what's wrong. Could be your idle sensor (or whatever it's called)

i agree, go to autozone .... at least you'll find out what's wrong with the car.

 

[moonshinemadness]

If its auto then putting it in reverse will make it shudder as for the engine idle change, does it have air con? if so everytime the air con cuts in the engine speed increses.

 

[rh71]

AutoZone reads the check engine light code for free ?

 

[kami333]

Maybe, I know Pep Boys will.

 

[Analog]

Originally posted by: rh71
AutoZone reads the check engine light code for free ?

yes. It may be the IAC valve.

 

[eplebnista]

Originally posted by: rutchtkim
i always get that with my cars. even new ones. i just ignore them.

Ditto