Diagnostic Code 13-'89 olds ciera

[minimoto]

I'm trying to get my '89 olds ciera 3.3L to pass motor vehicle inspection in Texas, but you need an RPM below 1200 in neutral to take the test and mine won't go under 1300.

So I checked the diagnostic codes and got a code 13, which, according to one website, means that the "Oxygen sensor voltage stays between 0.35 and 0.55 volts for 30 seconds with a throttle angle above 4% after engine had been running for at least 40 seconds..." Is this good or bad news?

Any ideas on how to get my RPM under 1200?

[maxwedge]

Welcome to AF, first code 13 is almost always a bad sensor or wiring to it, second the high idle could be a carboned up throttle body, sticking, dirty iac, or bad temp sensor, so someone has some work cut out for them. A scan will tell you if the iac is active, clean the iac and passages and the throttle body, check the connector to o2, if ok replace it.

[minimoto]

Thank you for your swift reply!

I checked the IAC (the thing with the spring wound around it) and it was covered in what I would call carbon black, like you get on the bottom of your pots and pans. It wasn't greasy or gunky so I didn't think it was bad. Is this black stuff bad and should I remove it? Thanks again.

[maxwedge]

Carb cleaner will do, also clean out the passages in the tb.

[minimoto]

Thanks, I'll put carb cleaner on my shopping list. In the meantime, after having my oxygen sensor replaced I'm still getting a code 13 and not only that, my tachometer doesn't go to zero when the engine is shut off. Should I take it back to the shop?