DTC Troubleshooting: P0138 (63)
  1. Check for continuity between ECM connector terminal C27 and body ground.
Is there continuity?
YES -
Go to Step 29 .
NO -
Repair open in the wire between the ECM (C27) and the secondary HO2S (Sensor 2), then go to Step 21 .
  1. Turn the ignition switch to LOCK (0).
  1. Replace the secondary HO2S (Sensor 2).
  1. Reconnect all connectors.
  1. Turn the ignition switch to ON (II).
  1. Reset the ECM with the HDS.
  1. Do the ECM idle learn procedure.
  1. Start the engine. Hold the engine speed at 3,000 rpm (min −1 ) without load (in neutral) until the radiator fan comes on, then let it idle.
  1. Test-drive under these conditions:
    • Engine coolant temperature (ECT SENSOR 1) above 70 °C (158 °F)
    • Transmission in 4th gear
    • Engine speed between 1,500−3,000 rpm (min −1 )
    • Drive about 1 minute or more
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0138 indicated?
YES -
Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM, then go to Step 1 .
NO -
Go to Step 28 .
  1. Monitor the OBD STATUS for DTC P0138 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
Troubleshooting is complete. If any other Temporary DTCs or DTCs ware indicated in Step 27 , go to the indicated DTC's troubleshooting.■
NO -
If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM, then go to Step 1 . If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to Step 25 .
  1. Reconnect all connectors.
  1. Update the ECM if it does not have the latest software, or substitute a known-good ECM.
  1. Start the engine. Hold the engine speed at 3,000 rpm (min −1 ) without load (in neutral) until the radiator fan comes on, then let it idle.
  1. Test-drive under these conditions:
    • Engine coolant temperature (ECT SENSOR 1) above 70 °C (158 °F)
    • Transmission in 4th gear
    • Engine speed between 1,500−3,000 rpm (min −1 )
    • Drive about 1 minute or more
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0138 indicated?
YES -
Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 31 . If the ECM was substituted, go to Step 1 .
NO -
Go to Step 34 .
  1. Monitor the OBD STATUS for DTC P0138 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. If any other Temporary DTCs or DTCs were indicated in Step 33 , go to the indicated DTC's troubleshooting.■
NO -
If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 31 . If the ECM was substituted, go to Step 1 . If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to Step 31 .