DTC Troubleshooting: P1166 (41-1)

DTC P1166 (41-1):  A/F Sensor (Sensor 1) Heater Circuit Malfunction

1.Reset the ECM/PCM.

2.Start the engine.

Is DTC P1166 indicated?


YES - Go to 3.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the ECM/PCM.n


3.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.n


NO - Go to 4.

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

 

Is there battery voltage?


YES - Go to 5.


NO - Go to 9.


5.Turn the ignition switch OFF.

6.Disconnect ECM/PCM connector A (31P).

7.Turn the ignition switch ON (II).

8.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.n


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


9.Turn the ignition switch OFF.

10.Disconnect ECM/PCM connector A (31P) and the A/F sensor (sensor 1) 4P connector.

11.Check for continuity between 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 the ECM/PCM (A22).n


NO - Go to 12.

12.Turn the ignition switch ON (II).

13.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) or A/F sensor relay.n


NO - Go to 14.


14.Check the following fuses:
  • No. 14 OPTION (40A) fuse in the under-hood fuse/relay box.
  • No. 4 ACG (10A) fuse in the under-dash fuse/relay box.
  • No. 15 +B LAF (A/F) HEATER (20A) in the 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.n


NO - Go to 15.


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

Is there continuity?


YES - The wires are OK, replace the A/F sensor relay.n


NO - Repair open in the wire between the A/F sensor relay and the fuses.n