Honda P0135-Primary HO2S Sensor 1 Heater Circuit Malfunction

Honda P0135 Primary Heated Oxygen Sensor HO2S Sensor 1 Heater Circuit Malfunction

Code P0135 Honda is DTC code indicating an issue with oxygen heater circuit in sensor 1 bank 1. The function of oxygen sensor is to monitor the amount of oxygen present in exhaust system and adjust fuel mixture accordingly. When heater circuit fails HO2S sensor may not be able to monitor correctly the oxygen levels in the exhaust system. When engine control module (ECM) detect problem with the heater circuit within HO2S sensor code p0135 stored in vehicle computer.

Fault Location- HO2S Sensor Sensor 1 Bank 1

Possible Causes Code P0135 Honda

1.The most common cause is failed HO2S sensor. The HO2S sensor may be damaged or it may have failed electrically.

2.Broken, loose connection or damaged wiring harness of HO2S sensor.

3.The HO2S sensor circuit is protected by fuse. If heater circuit fuse blows, heater circuit will be unable to function triggering p0135.

4.Vacuum leaks can cause HO2S sensor to give incorrect reading and trigger p0135.

5.In some rear cases engine control module (ECM) may be faulty causing p0135.

Honda P0135 DTC Code Possible Symptoms

1.Faulty HO2S sensor causes engine to run too rich or too lean resulting decreased fuel efficiency.

2.Engine may misfire causing rough idle and reduce engine performance.

3.Fault HO2S sensor can result in increased emissions.

4.Reduced acceleration and power resulting in poor overall engine performance.

5.Check engine light illuminates in dashboard.

How To Fix Code P0135 Honda

1.If HO2S sensor found faulty replace the sensor.

2.Any issue with wiring of HO2S sensor heated circuit such as loose connection, damaged wiring harness, broken or worn out wiring need to repaired or replaced.

3.Inspect and repair engine related issue such as vacuum leaks causing HO2S sensor to read incorrectly data.

4.Inspect engine control module (ECM) if found faulty need to be replaced.


Its important to have the vehicle inspected and diagnosed by professional mechanic to find and resolve issue related with p0135 for proper repair.

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