- The system will not set a code if the computer does not detect a fault in the heater circuit.
- The computer may not be able to detect a fault in the heater circuit if the sensor is not fully warmed up.
- The computer may not be able to detect a fault in the heater circuit if the problem is intermittent.
To troubleshoot this problem, you will need to use a scan tool to monitor the oxygen sensor heater circuit. The scan tool will display the voltage and current flowing through the circuit. You can then compare these values to the specifications for your vehicle. If the values are outside of specifications, then you will need to replace the oxygen sensor.
Here are the steps on how to check the oxygen sensor heater circuit:
- Disconnect the negative terminal on your battery.
- Make sure the engine is cool to the touch.
- Remove the exhaust pipe from the cylinder head.
- Locate the oxygen sensor.
- Unplug the electrical connector from the oxygen sensor.
- Touch the positive probe of a multimeter to the heater pin.
- Touch the negative probe of the multimeter to the ground pin.
- The multimeter will display the voltage in the circuit.
- Compare the voltage reading to the specifications for your vehicle.
- If the voltage reading is outside of specifications, then you will need to replace the oxygen sensor.
Here is a list of the possible causes for a code not setting for the catalyst oxygen sensor heater:
- Open or short circuit in the heater circuit
- Faulty oxygen sensor
- Damaged or disconnected wiring
- Faulty ECU
- Software issue with the ECU
