Honda Civic O2 Sensor Code Not Clearing Due to Power Issue in Heater Wire on Honda Civic

Some Honda Civic owners report experiencing issues with the O2 sensor code P0135, which indicates a malfunction in the Primary Heated Oxygen Sensor Heater Circuit due to a failed upstream O2 sensor heater element. These owners often find that testing the heater element is straightforward with a multimeter, eliminating the need for a scan tool. Additionally, it is crucial to check the power supply and ground on the heater circuit to ensure proper voltage reaches the sensor. Symptoms such as decreased fuel efficiency, rough idling, potential stalling, and problems during emissions tests may accompany the Malfunction Indicator Lamp (MIL) being illuminated. Failure to address the P0135 code can lead to poor fuel efficiency and increased exhaust emissions, negatively affecting vehicle performance. If wiring issues are ruled out, owners should proceed to test the resistance of the O2 sensor heater circuit for further diagnosis.