DTC Troubleshooting

DTC Troubleshooting: P0133

DTC P0133: A/F Sensor (Sensor 1) Malfunction/Slow Response

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

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

2. Clear the DTC with the HDS.

3. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

4. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)

- Transmission in 3rd or 4th

- Drive the vehicle at 25 mph (40 km/h) or less for 5 minutes, then drive at a steady speed between 26-81 mph (41-130 km/h).

5. Monitor the OBD STATUS for DTC P0133 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?
YES - Go to step 6.

NO - If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the ECM. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 3 and recheck.


6. Turn the ignition switch to LOCK (0).

7. Replace the A/F sensor (Sensor 1). A/F Sensor Replacement

8. Turn the ignition switch to ON (II).

9. Reset the ECM with the HDS.

10. Do the ECM idle learn procedure. ECM Idle Learn Procedure

11. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

12. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)

- Transmission in 3rd or 4th

- Drive the vehicle at 25 mph (40 km/h) or less for 5 minutes, then drive at a steady speed between 26-81 mph (41-130 km/h).

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

Is DTC P0133 indicated?
YES - Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the ECM, then go to step 1.

NO - Go to step 14.


14. Monitor the OBD STATUS for DTC P0133 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 13, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1) 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 11.