P1166
DTC P1166: A/F Sensor (Sensor 1) Heater Circuit Malfunction1. Reset the ECM.
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 terminals at the A/F sensor relay, the A/F sensor (Sensor 1), and the ECM.
3. check the following fuse:
- No.14 OPTION (30 A) fuse in under-hood fuel relay box.
- No. 2+B LAF (A/F) HEATER (20 A) fuse in under-dash fuse/relay box.
- No. 4 ACG (10 A) 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 connector terminals A1 and A24, 30 seconds after the ignition switch is turned ON (II).
Is there battery voltage?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO - Go to step 5.
5. Measure voltage between ECM 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 connector E (31P).
8. Turn the ignition switch ON (II).
9. Connect ECM connector terminal E8 to body ground with a jumper wire, then measure voltage between ECM connector terminals A1 and A24.
Is there battery voltage?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO - Repair open in the wire between the A/F sensor (Sensor 1) and ECM (A1).
10. Turn the ignition switch OFF.
11. Disconnect the ECM 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 (A22).
NO - Go to step 13.
13. Turn the ignition switch ON (II).
14. Measure voltage between ECM connector terminals E8 and A24.
Is there battery voltage?
YES - Repair open in the wire between the ECM (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.