Had the Service Engine Soon light come on, so I took it to the mechanic, he hooked it up and the only thing he could tell me was that it was an intermittent problem, and wouldn't be easy to find. He said there was a good chance it was an out of date PROM, mine was coded 8981. Does anyone know anything about this?

My engine light came on under quick acceleration, however I had done the same thing a couple times prior without problems. Car wasn't turned off in between, no obvious warnings before, and after the only difference was a sudden decrease in performance. The acceleration was MUCH more sluggish, but everything else seemed fine.

Does anyone know what this is? Easy fix? It's gone away and come back a couple times. If I let the car sit overnight it's fine.

BTW... it's a 1987 Caballero.

Get a competent mechanic. I've never heard of an out of date PROM.

Did he tell you what the SES code was? My first guess is the oxygen sensor is getting tired.

Get a competent mechanic. I've never heard of an out of date PROM.
He was my #2 choice mechanic. Does all the work for my mom's company. However my #1 choice keeps the family cars in working order. Only problem is he was backed up til tomorrow when I tried to get my car in.

Did he tell you what the SES code was? My first guess is the oxygen sensor is getting tired.
No he didn't. He said it was an intermittent problem and would be very difficult to find. And the oxygen sensor was my suspicion too.

Oxygen sensor codes, in my experience, are the only ones to come and go. The rest are usually hard faults.

You could hook a volt meter to it. It should quickly bounce back and forth between 0-5 volts.


You could stick a paperclip in the ALDL connector and read the codes yourself. Somewhere on the internet there has to be instructions on how to do this. Check www.montecarloss.com

No such thing as an out of date EPROM unless it's not the original ECM.

Somewhere on the internet there has to be instructions on how to do this.
Here is a good description of how to pull the SES codes.

http://www.elcaminocentral.com/article-55--0-0.html