Code 41: O2 Sensor Heater
- Turn ignition off. Remove BACK UP fuse from underhood fuse/relay box for 10 seconds to reset ECU. Check ECU for fault codes. See RETRIEVING CODES
. If Code 41 is not present, problem is intermittent. Check for poor connections at ECU connector and O2 sensor connector.
- Test drive vehicle and retest. If Code 41 is present, turn ignition off. Disconnect 4-pin O2 sensor connector. Measure resistance between O2 sensor terminals "C" and "D". See Fig 1
. If resistance is not 10-40 ohms, replace sensor. If reading is 10-40 ohms, go to step 3).
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Check continuity between body ground and O2 sensor terminals "C" and "D". If continuity is present, replace sensor. If continuity is not present, check for continuity between terminal "D" and terminal "A" and "B". If continuity is present, replace sensor.
- If continuity is not present, turn ignition on. Measure voltage between Yellow/Black (+) terminal and Orange/Black (-) at O2 sensor wiring harness connector. See Fig 1
. If battery voltage is not present, go to step 7). If battery voltage is present, disconnect connector "A" from ECU. Measure voltage between Yellow/Black (+) and Orange/Black (-) wires at O2 sensor wiring harness connector.
- If battery voltage is present, repair short circuit in Orange/Black wire between ECU connector terminal A6 and O2 sensor. If battery is not present, reconnect O2 sensor. Connect "A" connector of ECU Test Harness (07LAJ-PT3010A
) to vehicle wiring harness leaving ECU disconnected.
- Connect ammeter between test terminals A6 (+) and A23 (-). Monitor ammeter for 5 minutes. If current is less than 0.1 amp, replace O2 sensor. If current is not less than 0.1 amp, substitute a known good ECU, and recheck. If symptom/problem goes away, replace original ECU.
- If battery voltage was not present in step 4), measure voltage between Yellow/Black (+) terminal at O2 sensor wiring harness connector and body ground. If battery voltage is not present, repair open in Yellow/Black between O2 sensor and main relay. If battery voltage is present, turn ignition off. Reconnect O2 sensor wiring harness connector.
- Connect "A" connector of ECU Test Harness (07LAJ-PT3010A
) to vehicle wiring harness leaving ECU disconnected. Turn ignition on. Measure voltage between test terminals A6 (+) and A23 (-). If battery voltage is not present, repair open in Orange/Black wire between ECU connector terminal A6 and O2 sensor. If battery voltage is present, substitute a known good ECU, and recheck. If symptom/problem goes away, replace original ECU.