IAT reads -40

[thomsensnowboard]

I keep getting IAT codes for air intake temp sensor cicuit high, code is p0113
i can clear code out and datalog and still see -40 degrees tried new mas air flow and found that still reads -40, truck does have edge programmer, anybody know any wiring issues or anything? where do i start

 

[Fingers]

Use contact cleaner to clean your IAT/MAF sensor. Not sure where you are located, but in the winter months, ice can form on the sensor shorting it out. (thus the -40) Dirt and some oils can do the same thing, but you shouldn't be having those problems with a good filter. Water vapor, however, gets through any filter.

 

[ripmf666]

What year truck do you have ?

 

[jneal]

Use contact cleaner to clean your IAT/MAF sensor. Not sure where you are located, but in the winter months, ice can form on the sensor shorting it out. (thus the -40) Dirt and some oils can do the same thing, but you shouldn't be having those problems with a good filter. Water vapor, however, gets through any filter.

Correct me if I'm wrong, but isn't the IAT sensor located in the intake bridge towards the passenger side of the valley?

The reading you are getting is from the sensor curcuit being electrically open. The IAT sensor if I am thinking correctly has 2 wires that are very thin and easily breakable. I have had several break where the wires go into the sensor. Unplug the sensor, connector should be clipped to the the upper radiator metal pipe. Check resistance from terminal to terminal at the sensor. IIRC the resistance should be 1.4k at around 68 degrees. You'll probably get a open reading or Mega ohms, meaning the circuit it open. If so replace the sensor.

 

[Fingers]

Correct me if I'm wrong, but isn't the IAT sensor located in the intake bridge towards the passenger side of the valley?

The reading you are getting is from the sensor curcuit being electrically open. The IAT sensor if I am thinking correctly has 2 wires that are very thin and easily breakable. I have had several break where the wires go into the sensor. Unplug the sensor, connector should be clipped to the the upper radiator metal pipe. Check resistance from terminal to terminal at the sensor. IIRC the resistance should be 1.4k at around 68 degrees. You'll probably get a open reading or Mega ohms, meaning the circuit it open. If so replace the sensor.

MAF has an integrated IAT sensor. LBZ and later also have a sensor post grid heater IIRC. The higher the resistance, the higher the IAT. Low resistance would normally indicate a low temperature.

 

[jneal]

Opps, I was thinking wrong on the sensor readings then. I thought as temp went up resistance went down and vise versa.

 

[thomsensnowboard]

its intgated into the maf, i guess im going to try to over lay a wire from my maf to the pcm and see what happens, took the maf out of my brothers truck both same year and same motor LLY engines, hopefully its not a pcm

 

[Killerbee]

It's been a while since I did this, but as I recall, the reading at the MAF sensor is AAT. IAT is well downstream after CAC.

This is 06 and on, using EFILive to evaluate heat conditions, not sensor voltage specifically, so Jon if your information conflicts with this (voltage verification) then I would like to know.

 

[Fingers]

its intgated into the maf, i guess im going to try to over lay a wire from my maf to the pcm and see what happens, took the maf out of my brothers truck both same year and same motor LLY engines, hopefully its not a pcm

So it is an '04.5 or '05 LLY. The IAT is taken at the MAF on this and the LB7s.

I would check both the power feed (+12 Volts) and the ground at the sensor. Since the MAF and IAT share the same supply voltage, you might want to check you MAF readings.

 

[Fingers]

It's been a while since I did this, but as I recall, the reading at the MAF sensor is AAT. IAT is well downstream after CAC.

This is 06 and on, using EFILive to evaluate heat conditions, not sensor voltage specifically, so Jon if your information conflicts with this (voltage verification) then I would like to know.

That is true of '06 and later. An additional temp sensing point was placed post grid heater. The original MAF temp sensing point was also retained. I am looking up the nomenclature now.

 

[Killerbee]

I did not catch that it was an LLY. disregard.

Interested in nomenclature source also.

 

[Fingers]

For LBZ on, the sensors are dubbed IAT and IAT2 in the SI manual. The MAF sensor location retains the IAT moniker in the GM lit. However, EFI coined the AAT (Ambient Air Temp) designation for the MAF temperature point and just IAT for the manifold temp sensor. Clear as mud

 

[Killerbee]

"ambient" air temp, measured under hood, has always been silly to me. I wonder where these terms come from. I like IAT, and IAT2 better, but this assertion is probably too late for the software.