DTC P2A00: A/F Sensor (Sensor 1) Range/Performance Problem

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158°F (70°C)
- Transmission in D
- Vehicle speed between 25-55 mph (40-88 km/h) for 5 minutes
- Drive at a steady speed between 55-75 mph (88-120 km/h) for 10 seconds, then decelerate (with the throttle fully closed) for 5 seconds
Monitor the OBD STATUS for DTC P2A00 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 A/F sensor (Sensor 1) and the PCM. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION or NOT COMPLETED, go to step 3 and recheck.
Turn the ignition switch to LOCK (0).
Replace A/F sensor (Sensor 1) (see A/F SENSOR REPLACEMENT ).
Turn the ignition switch to ON (II).
Reset the PCM with the HDS.
Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158°F (70°C)
- Transmission in D
- Vehicle speed between 25-55 mph (40-88 km/h) for 5 minutes
- Drive at a steady speed between 55-75 mph (88-120 km/h) for 10 seconds, then decelerate (with the throttle fully closed) for 5 seconds
Check for Pending or Confirmed DTCs with the HDS.
Is DTC P2A00 indicated?

YES -Check for poor connections or loose terminals at A/F sensor (Sensor 1) and the PCM, then go to step 1.

NO -Go to step 13.
Monitor the OBD STATUS for DTC P2A00 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 12, go to the indicated DTC's troubleshooting.

NO -If the screen indicates FAILED, check for poor connections or loose terminals at A/F sensor (Sensor 1) and the PCM, then go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION or NOT COMPLETED, go to step 11.