KOER codes 12 and 13

[flainn]

I did my first KOER test this afternoon and got codes 12 and 13.

12 is “RPM [at idle] not within self-test upper limit”

13 is “RPM [at idle] not within self-test lower limit”

My truck has been idling high since I got it, but otherwise is running great.

I don't understand how both those codes can be true at the same time, unless maybe that means a sensor is sending no signal at all. ?

 

[92exp4x4]

I posted in your fuel economy thread, but since you opened this one too, I'll repost here.

I can't explain why the codes read both ways, but I would check the Idle air control valve for carbon buildup. You can remove it and clean it out. I did this on my first Explorer and it seemed to help alot.

 

[flainn]

I posted in your fuel economy thread, but since you opened this one too, I'll repost here.

I can't explain why the codes read both ways, but I would check the Idle air control valve for carbon buildup. You can remove it and clean it out. I did this on my first Explorer and it seemed to help alot.

Will do. Thanks again.

 

[flainn]

Ok, I took the IAC off the manifold and cleaned both ports with B-12 Chemtool, got a lot of carbon out of there and it looks a lot cleaner now.

Put it back on the truck and started it -- no change. When it starts it immediately revs to 1500-2000 RPM, then quickly drops back down but not below 1100 or so. When I put it in drive, it drops to 900 or 1000.

I ran another KOER test after going for a drive, and it's still throwing codes 12 and 13.

Maybe a bad IAC valve?

 

[MrShorty]

I haven't found those codes to be very useful, especially if they are the only codes. On one occasion, my little helper turned the steering wheel during the KOER test, and I got one or both of those codes just from the load of the power steering pump. With no other codes, I would treat any other symptoms that are present.

Which leads to the "high" idle. How cold is it? In cold weather, most engines will rev up and maybe run high until the engine gets warmed up a little bit. The main other causes for high idle are vacuum leaks and problematic throttle position sensors. You might hook up a good tachometer to make sure those engine speeds are accurate. They don't seem that high to me. In the absence of any other symptom, I might keep an eye on it until the problem becomes something easier to track down.

 

[flainn]

Which leads to the "high" idle. How cold is it? In cold weather, most engines will rev up and maybe run high until the engine gets warmed up a little bit. The main other causes for high idle are vacuum leaks and problematic throttle position sensors. You might hook up a good tachometer to make sure those engine speeds are accurate. They don't seem that high to me. In the absence of any other symptom, I might keep an eye on it until the problem becomes something easier to track down.

I guess it was in the thirties this afternoon when I was doing the test -- but I did the KOER after the truck was definitely warmed up (15-minute drive and had it up to 75 MPH, coolant temperature right in the middle of the range).

I'm only really concerned about it because it's annoying (shifting from park to reverse or from park to drive is jarring with the RPMs so high) and because I suspect it's affecting my fuel economy. But it's not a critical problem.