## DTC Troubleshooting: P0137 (63)

DTC P0137: | Secondary HO2S (Sensor 2) Circuit Low Voltage

1. | Turn the ignition switch ON (II).

2. | Do the DTC CLEAR in the CLEAR MENU with the HDS.

3. | Start the engine. Hold the engine speed at 3,000 rpm (min-1) with no load (in neutral) until the radiator fan comes on, then let it idle.

4. | Check the HO2S S2 in the DATA LIST with the HDS at the engine speed 3,000 rpm (min-1). Does the voltage stay at 0.1 V or less? YES - Go to 4. NO - Intermittent failure, system is OK at this time.Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM.n

5. | Turn the ignition switch OFF.

6. | Disconnect the secondary HO2S (Sensor 2) 4P connector.

7. | Start the engine.

8. | Check the HO2S S2 in the DATA LIST with the HDS at the engine speed 3,000 rpm (min-1). Does the voltage stay at 0.1 V or less? YES - Go to 8. NO - Go to 12.

9. | Turn the ignition switch OFF, and wait 10 seconds.

10. | Disconnect ECM connector No. 4 (40P).

11. | Check for continuity between secondary HO2S (Sensor 2) 4P connector terminal No. 2 and body ground. Is there continuity? YES - Repair short in the wire between the ECM connector No. 4 terminal No. 23 (test pin box terminal No. 104) and the secondary HO2S (Sensor 2), then go to 14. NO - Go to 20.

12. | Turn the ignition switch OFF.

13. | Replace the secondary HO2S (Sensor 2).

14. | Reconnect all connectors.

15. | Turn the ignition switch ON (II).

16. | Do the ECM RESET in the CLEAR MENU with the HDS.

17. | Do the ETCS learn procedure.

18. | Start the engine. Hold the engine speed at 3,000 rpm (min-1) with no load (in neutral) until the radiator fan comes on, then let it idle.

19. | Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS. Are any Temporary DTCs or DTCs indicated? YES - If DTC P0137 is indicated, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting. NO - Troubleshooting is complete.n

20. | Substitute a known-good ECM.

21. | Start the engine. Hold the engine speed at 3,000 rpm (min-1) with no load (in neutral) until the radiator fan comes on, then let it idle.

22. | Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS. Are any Temporary DTCs or DTCs indicated? YES - If DTC P0137 is indicated, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting. NO - Replace the original ECM.n