I started getting KOER code 116 (intake temperature higher or lower than expected) awhile ago. No KOEO or CM codes. I checked the wiring to the Intake Air Temperature sensor and it checked out. I checked the sensor it was bad and I replaced it. I removed ground from battery, cleared codes and checked again and passed. I checked my codes about 2 weeks later and it was back again!?! I have a K&N FIPK intake and Flex-a-Lite dual electric fans (yes their working) could this be a factor? Both aftermarket upgrades have been in very a year or more with no problems so I doubt their the problem......

 

Anyone? Greystreak? I'm wondering if my aftermarket fans maybe be cooling the intake air more than the sensor expects?

 

Ok, ok, gimme a sec... busy weekend folks. Ok, Code 116 (Code 24 on two-digit PCM's). First off, ANY intake air temps below 50 F and above 250 F will trigger this code! Therefore it is imperative that the engine be at op. temp. when the diagnostic test are administered. Assuming that is the case, you can verify resistance of the AIT/ACT sensor using the following as a general reference:

Degrees F - OHMs
50 - 58,750
68 - 37,300
86 - 24,270
104 - 16,150
122 - 10,970
140 - 7,700
158 - 5,370
176 - 3,840
194 - 2,800
212 - 2,070
230 - 1,550
248 - 1,180
Please not that due to variances in sensors and
air temperature readings, these numbers
are for reference only and should not be taken
as literal values. As long as the readings are
similar, the AIT/ACT sensor is probably good.

Assuming the sensor is good, Check the VREF signal at pin 25 of the ECM. You should get about +5VDC between it and ground. If you do not have this reading at pin 25 the ECM is suspect. If you do have this reading, at pin 25 double check the signal wiring by jumping the VREF wire and the return signal wire at the ACT connector. If the reading at pin 25 drops to zero, the wiring to the sensor is fine. If not you have wiring damage between the ECM and the sensor connector.

I know, that's my typical "way more info than we ever wanted there, GS" answer but I've dealt with this one personally before.

 

Thanks greystreak, you can never have too much info. I originaly checked the ref voltage at the sensor to ground and got a solid +5v. The original sensor didn't seem to change resistance with temp so I replaced it and didn't get the code again. I adjusted the temp setting on my fans not too long ago, im thinking now that they just work so good that the engine temp doesn't get high enough from doing its normal 30 sec warmup cycle to do the test properly. I drove to the store to get the new sensor, so the engine was nice and warm when I installed the new unit and reran the test. When the code came back I think I just did the 30 sec warmup again. This never turned in the past though even with the electric fans.

 

Hmm, I suppose it's possible. How cold is it by you these days? Keep in mind that if the incoming air is significantly cooler, it will take longer for the intake itself to warm up. The metal of the intake draws heat from the engine as it warms up but from dead cold with significantly cooler temps and your extremely efficient cooling fans, this could be contributing to cooler ACT temps. Cool enough to trigger Code 116? Hard to tell. If you are uncertain, you might "warm up" the fan settings and see if things straighten themselves out. This could be something you will need to watch depending upon the ambient air temperature if it does.

Kinda makes you think it would be interesting to fabricate some way of chilling the upper intake plenum runners when the weather is hot to help with performance. But that's an idea for another day. CAI will have to do for now.

 

I'm going to start by running KOER after the 30 sec warmup, and then drive around for a few minutes and try again again to see if I can get a 116 with the engine thoroghly warmed up. If it turns out to be the case i'll just make sure to warm the engine better before running KOER because the adjustment on the fans is very sensitive to adjustment. I'm in North Texas so the temp is all over the place.

 

Good luck with it. I'd be interested to know what the issue ends up being. I've dealt with this and ECT sensor problems. Being thermistors they are the most susceptible to "out of range" readings either due to atmospheric conditions or resistance degradation due to age and exposure to the elements.

 

Well i've had alot of things more pressing lately so I just got around to settling this once and for all. The ground point beside the battery on the fender was disconnected and that waas enough to through the sensor off. The old sensor was in sad shape so im glad I changed it out anyways. I actually came across a thread from a few years ago where you mentioned this Greystreak. All 1's now!