DTC P0125: ECT Sensor 1 Malfunction/Slow Response Honda Pilot II

Note. Before you troubleshoot, record all freeze data and any on-board snapshot, and review GENERAL TROUBLESHOOTING INFORMATION .

1. Start the engine, and let it idle for 5 minutes or more.
2. Check ECT SENSOR 1 in the DATA LIST with the HDS. Is about 0°F (-18°C) or less indicated? YES - Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM. If the connections and terminals are OK, replace ECT sensor 1 (see «ECT SENSOR 1 REPLACEMENT»(ref-333558-S23945314452009072100000) ). NO - Go to step 3 .
3. Turn the ignition switch to LOCK (0).
4. Allow the engine to cool to 104°F (40°C) or less.
5. Start the engine, and let it idle until ECT SENSOR 1 is about 158°F (70°C). Does ECT SENSOR 2 also show about 158°F (70°C)? YES - Go to step 6. NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM.
6. Check the thermostat (see «THERMOSTAT TEST»(ref-333555-S29536171512009072100000) ). Is the thermostat OK? YES - Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM. If the connections and terminals are OK, replace ECT sensor 1 (see «ECT SENSOR 1 REPLACEMENT»(ref-333558-S23945314452009072100000) ), then go to step 8 . NO - Replace the thermostat (see «THERMOSTAT REPLACEMENT»(ref-333555-S20319323142009072100000) ), then go to step 8 .
7. Turn the ignition switch to ON (II).
8. Reset the PCM with HDS.
9. Turn the ignition switch to LOCK (0)
10. Allow the engine to cool to 104°F (40 °C) or less.
11. Start the engine, and let it idle until ECT SENSOR 1 goes up to about 158°F (70°C). Does ECT SENSOR 2 also show about 158°F (70°C)? YES - Go to step 1 and recheck. NO - Troubleshooting is complete.