DTC Troubleshooting: P0123 (7-2)

DTC P0123 (7-2):  TP Sensor Circuit High Voltage

1.Turn the ignition switch ON (II).

2.Check the throttle position with the HDS or the scan tool.

Is there about 10% or 0.5 V when the throttle is fully closed and about 90% or 4.5 V when the throttle is fully opened?

YES - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the TP sensor and at the ECM/PCM.n

NO - Go to 3.

3.Turn the ignition switch OFF.

4.Disconnect the TP sensor 3P connector.

5.Turn the ignition switch ON (II).

6.At the wire harness side, measure voltage between the TP sensor 3P connector terminals No. 1 and No. 3.


Is there about 5 V?

YES - Replace the throttle body (the TP sensor is not available separately).n

NO - Go to 7.

7.Measure voltage between ECM/PCM connector terminals A10 and A20.


Is there about 5 V?

YES - Repair open in the wire between the ECM/PCM (A10) and the TP sensor.n

NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original  ECM/ PCM.n