Need help with code 412

[CHH777]

Engine runs rough at idle with intermittent missing. Runs fine above idle. Pulled the following code with scanner:

412
Cannot control RPM during Engine Run Self-Test -- high RPM check.


No vacuum leaks and O2 sensors are new. Any ideas?

 

[MrShorty]

idle speed control motor?

 

[oahrens]

Did you reset the computer after replacing the O2's...can't hurt.

 

[CHH777]

MrShorty,

You mean idle air control valve? Can it be tested?


Computer has been reset multiple times.

 

[MrShorty]

Sorry, Chilton calls it idle air control valve, Haynes calls it idle speed control motor, and Haynes was the most recent reference I had used relating to this part.
Chilton says you need only check the resistance on it; should be 7-13 ohms. It also says you need to be aware of the polarity, because there is a diode inside.

 

[CHH777]

Update

Thanks for the test info.

I found a substantial exhaust leak in the driver side header. Borla is shipping a new set under warranty. Could this affect the O2 sensor on that side?

 

[MrShorty]

Leaking exhaust could affect the O2 sensor's reading. A large leak would also affect the back pressure in the exhaust system. I don't understand it myself, but I've seen others talk about the need for back pressure in the exhaust system for the engine to run properly, especially at low RPM. A large leak would significantly decrease this back pressure. Maybe someone else can enlighten us just how the back pressure is necessary?