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Crew,

I have a 2006 Pontiac G6 GT, 3.5 Liter V6 with 150,000+ miles on it.

Sometime in June we cleaned out the EGR Valve and throttle body. About a month ago, after passing inspection, I got the engine light and the ODB code was a P0113. The car shifts into gear pretty hard (Park to Drive, Neutral to Park, etc) and when shifting from 1st to 2nd. It's very aggressive at low RPMs (Think traffic jam highway situations).
When I clear the code, the car shifts as smooth as butter, but slowly degrades back to the normal rough shifting through the week, sometimes 8 hours after.

I purchased the Mass Air Flow Unit (Includes IAF sensor) and replaced it. The P0113 code is still being thrown after 8 hours of being cleared, just like before.

Has anyone had this issue, or does anyone have a clue on what's next?
 

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I have not had the issue or any first hand experience. The hard shifting sounds like the car has gone into limp mode because of the IAT error. From what I can find, P0113 is an open circuit, high resistance or short to voltage condition. Assuming the replacement part is good, that would leave a wiring, connection to ECM or ECM fault. The testing information I have would require a scan tool capable of displaying the current IAT reading. Perhaps it will give you a few ideas. Best of luck with the fix

Diagnostic Aids

Ignition ON, if the engine is cold, a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the mass air flow (MAF) sensor heating elements.
Depending on the ambient temperature, an IAT sensor signal circuit or low reference circuit that is shorted to the MAF sensor signal circuit can cause a DTC P0113 to set. This condition causes a rapid fluctuation in the IAT Sensor parameter.
An IAT sensor signal circuit that is shorted to the MAF sensor ignition circuit can cause a DTC P0113 to set.​
Circuit/System Verification

If the ignition has been OFF for 8 hours or greater , the IAT and the ECT should be within 15°C (27°F) of each other and also the ambient temperature. Ignition ON, observe the scan tool Start-up ECT and Start-up IAT Sensor parameters. Compare those sensor parameters to each other and also to the ambient temperature to determine if the IAT sensor is within an acceptable operating range.
Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current ambient temperature and the vehicle operating conditions.​
Circuit/System Testing
Ignition OFF, disconnect the harness connector at the IAT sensor.
Ignition OFF for 90 seconds , test for less than 5 ohm of resistance between the low reference circuit terminal E and ground.
¤ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the engine control module (ECM).

Ignition ON, verify the scan tool IAT parameter is less than -39°C (-38°F) .
¤ If greater than the specified range, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the ECM.

Install a 3A fused jumper wire between the signal circuit terminal D and a good ground. Verify the scan tool IAT parameter is greater than 149°C (300°F) .
¤ If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

If all circuits test normal, test or replace the IAT sensor.
Component Testing

Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature Vs Resistance table.
 
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