P1166

DTC P1166: A/F Sensor (Sensor 1) Heater Circuit Malfunction

1. Reset the ECM/PCM.
2. Start the engine.

Is DTC P1166 indicated?

YES - Go to step 3.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at C101 (located under the right side of the dash), C401 (located under the left side of the dash), C402 (located under under the left side of the dash) the A/F Sensor relay, the A/F Sensor (Sensor 1) and the ECM/PCM.

3. Check the following fuse:
- No.14 OPTION (30A) fuse in under-hood fuse/relay box.
- No.2+B LAF HEATER (20A) fuse in under-dash fuse/relay box.
- No. 4ACG (10A) in under-dash fuse/relay box.

Are any of the fuses blown?

YES - Repair short in the wire between the A/F Sensor relay and the fuses.

NO - Go to step 4.




4. Measure voltage between ECM/PCM connector terminals A1 and A24, 30 seconds after the ignition switch is turned ON (II).

Is there battery voltage?

YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.

NO - Go to step 5.




5. Measure voltage between ECM/PCM connector terminals A22 and A24.

Is there battery voltage?

YES - Go to step 6.

NO - Go to step 10.

6. Turn the ignition switch OFF.
7. Disconnect ECM/PCM connector E (31P).
8. Turn the ignition switch ON (II).




9. Connect ECM/PCM connector terminal E8 to body ground with a jumper wire, then measure voltage between ECM/PCM connector terminals A1 and A24.

Is there battery voltage?

YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.

NO - Repair open or short in the wire between the A/F Sensor (Sensor 1) and ECM/PCM (A1).

10. Turn the ignition switch OFF.
11. Disconnect the ECM/PCM connector A (31P) and the A/F Sensor (Sensor 1) 4P connector.




12. Check for continuity between the A/F Sensor (Sensor 1) 4P connector terminal No.3 and body ground.

Is there continuity?

YES - Repair short in the wire between the A/F Sensor relay, A/F Sensor (Sensor 1) and ECM/PCM (A22).

NO - Go to step 13.

13. Turn the ignition switch ON (II).




14. Measure voltage between ECM/PCM connector terminals E8 and A24.

Is there battery voltage?

YES - Repair open in the wire between the ECM/PCM (A22) and the A/F Sensor (Sensor 1).

NO - Go to step 15.

15. Check for continuity in the wires between the A/F Sensor and the fuses.

Is there continuity?

YES - The wires are OK. Replace the A/F Sensor relay.

NO Repair open in the wire between the A/F Sensor relay and the fuses.