DTC P0112: INTAKE AIR TEMPERATURE SENSOR VOLTAGE TOO LOW
Monitor & Set Conditions
Intake Air Temperature (IAT) sensor voltage is monitored when the ignition is on and battery voltage is greater than 10.4 volts. DTC may be stored when IAT sensor voltage at ECM is less than .098 volt for greater than 2 seconds
Possible Causes
- Intermittent Wiring
- IAT Sensor
- IAT Sensor Signal Circuit Shorted To Ground
- IAT Sensor Signal Circuit Shorted To Sensor Ground
- ECM
Testing
1. Turn ignition on with engine off. Using DRBIII(R) scan tool, read IAT sensor voltage. If IAT sensor voltage is less than .5 volt, go to next step. If IAT sensor voltage is .5 volt or greater, go to step 5.
2. Turn ignition off. Disconnect IAT sensor harness connector. IAT sensor is located on driver's side rear corner of the cylinder head. Turn ignition on with engine off. Using scan tool, read IAT sensor voltage. If IAT sensor voltage is 4 volts or less, go to next step. If IAT sensor voltage is greater than 4 volts, replace IAT sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.
3. Turn ignition off. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Ensure IAT sensor harness connector is still disconnected. Using DVOM, measure resistance between ground and IAT sensor harness connector terminal "B" (Black/Red wire). If resistance is less than 100 ohms, repair short to ground in IAT sensor signal circuit. If resistance is 100 ohms or greater, go to next step.
4. Using DVOM, measure resistance between IAT sensor harness connector terminals. If resistance is less than 100 ohms, repair short to sensor ground in IAT sensor signal circuit. If resistance is 100 ohms or greater, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.
5. The conditions that set the DTC are not present at this time. With ignition on engine off, monitor DRBIII (R) scan tool parameters related to the DTC while wiggling wiring harness. Look for parameter values to change and/or a DTC to set. Review the DRBIII(R) Freeze Frame information. If possible, try to duplicate the conditions under which the DTC was set. Refer to any Technical Service Bulletins (TSB) that may apply. Visually inspect the related wire harness. Look for any chafed, pierced, pinched or partially broken wires. Visually inspect the related wire harness connectors. Look for broken, bent, pushed out or corroded terminals. Was any of the above conditions present? If yes, repair as necessary. If no, the test is complete.