DTC Troubleshooting: P0642 (133-3)

DTC P0642:  Sensor Reference Voltage A Circuit Low Voltage

1.Turn the ignition switch ON (II).

2.Clear the DTC with the HDS.

3.Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0642 indicated?


YES - Go to 4.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the FRP sensor, the MAF sensor/IAT sensor 1, the MAP sensor/IAT sensor 2, the APP sensor and the ECM.n


4.Turn the ignition switch OFF, and wait 30 seconds.

5.Disconnect the connectors from these sensors:
  • FRP sensor
  • MAF sensor/IAT sensor 1
  • MAP sensor/IAT sensor 2
  • APP sensor

6.Turn the ignition switch ON (II).

7.Clear the DTC with the HDS.

8.Reconnect the connector from each of these sensors, one at a time:
  • FRP sensor
  • MAF sensor/IAT sensor 1
  • MAP sensor/IAT sensor 2
  • APP sensor

9.Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0642 indicated?


YES - Replace the sensor that indicated DTC when reconnected, then go to 13.


NO - Go to 10.

10.Turn the ignition switch OFF, and wait 30 seconds.

11.Disconnect ECM connectors No. 1 (96P) and No. 2 (58P).

12.Check for continuity between body ground and ECM connector No. 1 terminals No. 8, No. 9, No. 33 and ECM connector No. 2 terminal No. 14 individually.

 

Is there continuity?


YES - Repair short in the wire between the ECM connector terminals and these sensors, then go to 13.

  • FRP sensor and ECM connector No. 1 terminal No. 9
  • MAF sensor/IAT sensor 1 and ECM connector No. 1 terminal No. 8
  • MAP sensor/IAT sensor 2 and ECM connector No. 1 terminal No. 33
  • APP sensor and ECM connector No. 2 terminal No. 14

NO - Go to 17.

13.Reconnect all connectors.

14.Turn the ignition switch ON (II).

15.Reset the ECM with the HDS.

16.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0642 is indicated, check for poor connections or loose terminals at the FRP sensor, the MAF sensor/IAT sensor 1, the MAP sensor/IAT sensor 2, the APP sensor and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Troubleshooting is complete.n


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

18.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0642 is indicated, check for poor connections or loose terminals at the FRP sensor, the MAF sensor/IAT sensor 1, the MAP sensor/IAT sensor 2, the APP sensor and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


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