DTC P0112 Or P0117 - Temperature Sensor Test (IAT & ECT): Condition

This DTC indicates sensor signal is less than self-test minimum. Minimum signal for IAT and ECT sensor is 0.2 volt. Possible causes for this fault are:

• Circuit grounded in wiring harness.
• Faulty sensor.
• Faulty connection.
• Faulty PCM.

1) Simulate Opposite Signal To PCM  Turn ignition off. Disconnect wiring harness connector from suspect sensor. Check for damaged wiring, and repair as necessary. With scan tool connected, turn ignition on. Using scan tool, access ECT V of IAT V PID. If PID is less than 4.2 volts, go to next step. If PID is 4.2 volts or more, replace sensor and repeat QUICK TEST.

2) Check VREF Circuit Voltage At TP Sensor  Turn ignition off. Disconnect TP sensor wiring harness connector. Turn ignition on. Measure voltage between VREF and SIG RTN at TP sensor wiring harness connector. If voltage is 4-6 volts, connect TP sensor and go to next step. If voltage is not 4-6 volts, repair open in VREF circuit.

3) Check Signal Circuit For Short To Ground  Turn ignition off. Disconnect suspect sensor. Disconnect PCM 104-pin connector. Check for damaged wiring, and repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT) or No. 25 (IAT) and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM and repeat QUICK TEST.