During engine startup, the engine control module (PCM/ECM/ECU), tests the oxygen heater circuit for excessive current, short circuits, and open circuits. The PCM will generate fault code P0135 if it detects an issue with the first sensor in the first row of the O2 Sensor Heater Circuit.
The O2 sensor monitors your vehicle’s air-fuel ratio. The computer in your vehicle uses this sensor’s information to control the fuel mixture, and to reduce emissions. However, it must be warm enough for the computer to do this. The O2 sensor is equipped with an integrated heater to quickly reach the temperature required when the engine starts cold. The P0135 fault is activated if this circuit fails to function correctly.
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What are the Symptoms of Fault Code P0135?
- Check Engine Light Illuminated
- There will not be any O2 Sensor feedback to the ECM unless the O2 Sensor transmits a message.
- The engine will run in an irregular manner until the exhaust heats up enough to activate the O2 Sensor.
- Engine misfiring
What are the Causes of Fault Code P0135?
- Short circuit or open circuit of the O2 heating circuit wiring or the element.
- Wiring harness damage or short circuit
- Faulty oxygen sensors
The engine control module (PCM/ECM/ECU), when you start your engine, tests the O2 Sensor Heater Circuit. The PCM will display the P0135 code if it detects a delay or fault.
How to Fix Fault Code P0135?
The problem may be resolved by replacing or resolving the O2 heater wiring issues or resistance. You can restore the O2 heating circuit or element to its original function by resolving issues with short circuits, open circuits, or high resistance. The oxygen sensor will need to replaced if an open circuit or short-circuit occurs. A faulty O2 can cause engine problems, such as increased emissions and reduced efficiency.
- Visually inspect the electrical connections and wiring harness of the O2 sensor in Bank 1 Sensor 1.
- The O2 sensor should be monitored in order to determine if the heater is working.
- Test the O2 sensor connector for the correct voltage input from the PCM.
- Test the resistance of the O2 Sensor Heater Circuit.
- The heater circuit fuse should be replaced after the short circuit has been rectified.
- Repair or replace the cable or connection to the O2 Sensor.
- Replace the O2 sensor.
P0135 Fault Code: Is It Significant?
O2 sensors are crucial in maintaining a proper air/fuel mix for a smooth engine. The O2 sensors are directly responsible for the PCM’s ability to adjust the fuel mix. The PCM will stay in open loop until the O2 system has been repaired. This will make the engine run richer, which consumes more fuel and creates carbon deposits.
