[billb303]

Ok, so I install a new fuel pump in my car and I get a check engine light. These are the codes that I get:

KOEO:

13 - Cannot control rpm during KOER Self-Test low rpm check.

31 - EVP circuit below minimum voltage.

67 - Park/Neutral Position (PNP) switch circuit open - A/C on during Self-Test.

KOER:

12 - Cannot control rpm during KOER Sell-Test high rpm check.

21 - ECT out of Self-Test range MAP/BARO out of Self-Test range.

31 - EVP circuit below minimum voltage.

91 - No HO2S switch detected (left HO2S).

I also recently pulled my throttle body and IAC off to clean them. Is it possible that I did something to cause this problem by doing that?

Would someone please elaborate on what these codes mean?

[neverfastenough1]

You got the numbers right, but they mean different things when the engine is off or on. The KOEO codes 13- idle speed control did not respond, 67- make sure your a/c is off, and 31 points to the EGR sensor. For the KOER test do it again with the engine at normal running temp. The codes 12 has to do with the ISC idle too low, 21, 31 and 91 to me all might be caused by the engine being cold. Have you done an EGR delete? You will get codes if you have.

[neverfastenough1]

91 is running lean, and I meant to say 31 points to egr valve position sensor. 12 and 13 point to the IAC which I believe could cause the 91. Tengram is better at this stuff.

[TENGRAM]

Originally Posted by billb303 KOEO: 13 - Cannot control rpm during KOER Self-Test low rpm check. 31 - EVP circuit below minimum voltage. 67 - Park/Neutral Position (PNP) switch circuit open - A/C on during Self-Test. KOER: 12 - Cannot control rpm during KOER Sell-Test high rpm check. 21 - ECT out of Self-Test range MAP/BARO out of Self-Test range. 31 - EVP circuit below minimum voltage. 91 - No HO2S switch detected (left HO2S).

12 and 13 are saying nearly the same thing, the ECM is having trouble controlling idle. this may be because your IAC is not functioning or your idle is set too high but this should be dealt with last since some of these other codes may be contributing to this problem.

31 - your EGR valve position sensor is sending a voltage value lower than the closed (minimum) value. this one won't cause any performance or driveability problems but it will make your CEL stay on.
to diagnose:
disconnect the EGR Valve Position sensor. with the key in the "on" position (but engine off) measure the voltage between the VREF and sigRTN pins on the harness side connector using this diagram:



the voltage should be about 5volts. if it is, plug the sensor back in and measure voltage between the EVP wire and the sigRTN wire. use these diagrams to ID the wires by color:
http://www.veryuseful.com/mustang/te...ng_Diagram.gif
http://www.veryuseful.com/mustang/te...ng_Diagram.gif

voltage should be between .25volts and .67volts. if its not, replace the sensor. if it is let me know


91 - your driverside o2 sensor is reading lean. this can cause pretty severe driveability and performance problems. to diagnose this one simplly swap this o2 to the passenger side, and move the passenger side o2 to the driverside. reset codes by disconnecting the battery for about 15 minutes and then recheck codes. if the code 91 no longer shows up, but a code 41 does, than that o2 sensor is faulty and needs to be replaced. if the 91 does show back up let me know

the 21 may simply be because the engine wasn't fully warmed up, if you think it was then let me know and we'll diagnose it.

67 - as "neverfastenough" said, make sure when you run the tests your A/C is turned off. also make sure the tranny was in neutral.

keep us updated

[billb303]

Well it turns out I am an idiot and forgot to plug my EGR valve position sensor back in. Sooooooo everything is fine now. I appreciate the detailed response TENGRAM, sorry to waste your time. It did lead me to the problem though.

[TENGRAM]

Originally Posted by billb303 Well it turns out I am an idiot and forgot to plug my EGR valve position sensor back in. Sooooooo everything is fine now. I appreciate the detailed response TENGRAM, sorry to waste your time. It did lead me to the problem though.

its ok still i suggest to check out that o2 sensor code

[billb303]

When I re-checked the codes, everything is fine, except it is still giving me the KOER 91 error code, which makes me think the O2 sensor is bad. Could this be causing my car to idle roughly especially when the engine is cold?

[TENGRAM]

Originally Posted by billb303 When I re-checked the codes, everything is fine, except it is still giving me the KOER 91 error code, which makes me think the O2 sensor is bad. Could this be causing my car to idle roughly especially when the engine is cold?

it could be what is causing the rough idle but it may or may not be the 02 sensor itself at fault. reason why i explained how to diagnose it before.

[billb303]

I went to switch my O2 sensors around and they both looked pretty old and crusty, so I bought a couple of new ones and put them in. I am now getting a 41 and a 91 KOER code, however, the car is idling/running better than before. Any ideas?

[billb303]

Anyone have any ideas?

[billb303]

Do you have any ideas on what may be causing the above problem TENGRAM?

[TENGRAM]

make sure your o2 ground wire is attached to the back of the heads or the firewall. it is the orange wire coming out of the harness behind your intake manifold. it has a ring terminal on the end of it. let me know


#19 on this diagram