Code 41 - Heated Oxygen Sensor (Ho2S) Heater
- Turn ignition off. Remove BACK-UP fuse (7.5-amp) from underhood fuse/relay box for 10 seconds to reset ECM. Retrieve codes. If Code 41 does not appear, problem is intermittent. Inspect for poor connections at ECM, HO2S, and wiring harness connectors.
- Test-drive vehicle, then retest. If Code 41 appears, turn ignition off. Unplug 4-pin HO2S connector. Measure resistance between HO2S terminals "C" and "D". See Fig 1
. If resistance is 10-40 ohms, go to next step. If resistance is not 10-40 ohms, replace sensor.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Test for continuity between body ground and HO2S terminals "C", and "D". If continuity exists, replace sensor. If continuity does not exist, check for continuity between terminal "D" and terminals "A" and "B". If continuity exists, replace sensor.
- If continuity does not exist, turn ignition on. Measure voltage between Yellow/Black (+) and Orange/Black (-) wire terminals at HO2S wiring harness connector. If battery voltage does not exist, go to step 7). If battery voltage exists, unplug connector "A" from ECM. Measure voltage between Yellow/Black (+) and Orange/Black (-) wires at HO2S wiring harness connector.
- If battery voltage exists, repair short circuit in Orange/Black wire between ECM connector terminal A6 and HO2S. If battery voltage does not exist, reconnect HO2S. Attach connector "A" of ECM Test Harness (07LAJ-PT3010A
) to vehicle wiring harness, leaving ECM disconnected.
- Connect ammeter between test terminals A6 (+) and A23 (-). Monitor ammeter for 5 minutes. If current is less than 0.1 amp, replace HO2S. If current is not less than 0.1 amp, temporarily substitute known good ECM, then retest system.
- If battery voltage did not exist in step 4), measure voltage between Yellow/Black wire terminal (+) at HO2S wiring harness connector and body ground. If battery voltage does not exist, repair open in Yellow/Black wire between HO2S and main relay. If battery voltage exists, turn ignition off. Reconnect HO2S wiring harness.
- Attach connector "A" of ECM Test Harness (07LAJ-PT3010A
) to ECM wiring harness, leaving ECM disconnected. Turn ignition on. Measure voltage between test terminals A6 (+) and A23 (-). If battery voltage does not exist, repair open in Orange/Black wire between ECM connector terminal A6 and HO2S. If battery voltage exists, temporarily substitute known good ECM, then retest system.