Trouble Code P1166??

[vinbeaver]

Does anyone know what that trouble code means and what parts I would need to replace or what should be done to resolve the issue. Thanks for all your help.

[TireMeltingRSX]

Solution: Replace your primary 02 sensor.

If that doesn't work move on to this:

Here are the steps you have to follow in order to figure out your issue. This will narrow down it is the O2 sensor, a problem in the wiring, or if the ECU is damaged. We have yet to see an O2 sensor not work so I am thinking your issue is somewhere else in the car.

Reset the ECM/PCM.
Start the engine. Is DTC P1166 (P0135)* Indicated? YES - Go to step 3. NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at C101 (located under the right side of the dash), C401 (located under the left side of the dash), C402 (located under the left side of the dash) the A/F Sensor relay, the A/F Sensor (Sensor 1) and the ECM/PCM.
Check the following fuse:
No.14 OPTION (30A) fuse in under-hood fuse/relay box.
No.2 + B LAP HEATER (20A) fuse in under-dash fuse/relay box.
No.4 ACG (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.
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.

Measure voltage between ECM/PCM connector terminals A22 and A24. Is there battery voltage? YES - Go to step 6. NO - Go to step 10.
Turn the ignition switch OFF.
Disconnect ECM/PCM connector E (31 P).
Turn the ignition switch ON (II).

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).
Turn the ignition switch OFF.
Disconnect the ECM/PCM connector A (31 P) and the A/F Sensor (Sensor 1) 4P connector.
Check for continuity between the A/F Sensor (Sensor 1) 4P connector terminal No.3 and body ground. 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.
Turn the ignition switch ON (II).

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. 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.

Sounds like a pain in the ass. The info above is not my own, so I might not be able to help if you have any questions.

Dean, does that sound about right?

[C25A1guy]

Yes, P1166 is a AF sensor heater circuit is dead. If you have k-pro, you can turn this off. Otherwise, you will need Denso part number 234-9064 (unless otherwise superseded). Replacement is easy, as both the AF sensor and O2 sensor are in the cat pipe.
Tools needed:
Jack
jack stands
Ratchet
O2 sensor socket
Lube
Pencil flat head screw driver
Possibly a mallet or hammer

Removal
Preface: As always, when working on a sensor that monitors the engine vitals, always disconnect the negative terminal on the battery. This allows the ECU to remove any soft codes as well as recalibrate itself to the new sensor.
1: Jack the car up and place jack stands
2: allow exhaust system to cool
3: spray lube on AF sensor (sponsor plug: I use Torco PL-50 penetrating lube)
4: Disconnect sensor from engine harness
5: Use ratchet and O2 sensor socket, remove AF sensor. If AF sensor is seized, remove ratchet and stock, spray more lube on sensor. Then replace ratchet and socket on the sensor. Using a mallet or hammer, tap the handle of the ratchet until sensor breaks loose.
6: remove the sensor

Installation:
1: apply anti-seize compound on the threads of the new sensor. Do not allow anti-seize compound to touch the sensor head. Do not touch the sensor head. Do not ingest the anti-seize compound. Do not rub the anti-seize compound into your eyes. Do not use the old sensor as a sex toy.
2: install new sensor into the sensor bung, making sure not to cross thread and snug the sensor down with your ratchet and O2 sensor socket
3: route the sensor wires in the same OEM fashion. In some cases, you may need to transfer a rubber mount bushing from the factory sensor wire to the new sensor.
4: Plug sensor to wire harness
5: lower car back down. Start engine. Using K-Pro Manager, Honda Scantool, or any other OBD-II scan tool, check for codes. If there is a O2 or AF sensor code erase said code.