DTC Troubleshooting: P2138 (37)

DTC P2138:  APP Sensor A/B Incorrect Voltage correlation


1.Turn the ignition switch ON (II).

2.Check the APP SENSOR-A and APP SENSOR-B in the DATA LIST with the Honda PGM Tester or the HDS.

Does APP SENSOR-A and APP SENSOR-B change in the same throttle angle when the throttle is fully opened?


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


NO - Go to 3.


3.Check the APP SENSOR-A and APP SENSOR-B in the DATA LIST with the Honda PGM Tester or the HDS.

Are they the same voltage?


YES - Go to 4.


NO - Go to 9.


4.Turn the ignition switch OFF.

5.Jump the SCS line with the Honda PGM Tester or the HDS.

6.Disconnect the APP sensor 6P connector.

7.Disconnect ECM/PCM connector A (31P).

8.Check for continuity between ECM/PCM connector terminals A25 and A26.

Is there continuity?


YES - Repair short in the wire between the ECM/PCM (A25) and the ECM/PCM (A26), then go to 11.


NO - Go to 16.


9.Turn the ignition switch OFF.

10.Replace the APP sensor.

11.Reconnect ECM/PCM connector A (31P).

12.Turn the ignition switch ON (II).

13.Do the ECM/PCM RESET in the CLEAR MENU with the Honda PGM Tester or the HDS.

14.Do the ECM/PCM idle learn procedure.

15.Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM Tester or the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P2138 is indicated, check for poor connections or loose terminals at the APP sensor and the ECM/PCM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - Troubleshooting is complete.n

16.Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.

17.Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM Tester or the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P2138 is indicated, check for poor connections or loose terminals at the APP sensor and the ECM/PCM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM.n