DTC P0063 HO2S Heater Control Circuit Low Bank 2 Sensor 3

DTC P0063 is a diagnostic trouble code indicating an issue with the heater control circuit of the Heated Oxygen Sensor (HO2S) located at Bank 2 Sensor 3. Understanding and addressing this issue is crucial for maintaining your vehicle’s emissions control and overall engine performance. In this article, we’ll delve into the details of DTC P0063, exploring what it means, its potential causes, and how to diagnose and fix this issue effectively.

What is DTC P0063?

The P0063 diagnostic trouble code (DTC) signifies that there is a problem with the heater control circuit of the Heated Oxygen Sensor (HO2S) located at Bank 2 Sensor 3. Specifically, the code indicates that the heater circuit voltage is too low. The oxygen sensor heater helps the sensor reach its operating temperature quickly after the engine starts, allowing it to provide accurate readings sooner. When the ECU detects that the heater control circuit voltage is lower than expected, it sets the P0063 code. This can affect the sensor’s ability to monitor the exhaust gases accurately, leading to suboptimal air-fuel mixture adjustments.

Potential Causes of DTC P0063:

The P0063 code is triggered when the ECM detects a low voltage in the heater control circuit for the HO2S at Bank 2 Sensor 3. This can happen due to several reasons:

  • Faulty Oxygen Sensor Heater: The heater element within the sensor may be defective, leading to a low voltage condition.
  • Wiring Issues: Damaged, corroded, or shorted wiring in the heater control circuit can cause a drop in voltage.
  • Connector Problems: Loose, corroded, or damaged connectors can disrupt the heater control circuit.
  • ECU Issues: Although rare, a malfunctioning ECU could incorrectly interpret the control circuit status.

Symptoms of P0063

When the P0063 code is set, you might experience the following symptoms:

  • Check Engine Light (CEL) illuminated on the dashboard.
  • Possible decrease in fuel efficiency.
  • The vehicle may take longer to enter closed-loop operation, affecting performance shortly after startup.
  • Increased emissions due to delayed sensor activation.

Diagnostic and Repair Procedures for DTC P0063:

Diagnosing and resolving the P0063 code requires a systematic approach:

  1. Initial Inspection: Connect a diagnostic scanner to the vehicle’s OBD-II port to retrieve the trouble codes, including P0063. Record any additional codes and freeze frame data to understand the conditions under which the code was set.
  2. Visual Inspection: Conduct a thorough visual inspection of the HO2S at Bank 2 Sensor 3 and its wiring harness. Look for signs of damage, corrosion, or disconnections.
  3. Check Sensor Heater Resistance: Use a multimeter to measure the resistance of the heater element in the oxygen sensor. Compare the readings to the manufacturer’s specifications. Replace the sensor if the resistance is outside the acceptable range.
  4. Inspect Wiring and Connectors: Check the wiring and connectors associated with the HO2S heater control circuit for continuity and proper connection. Look for loose connections, short circuits, or broken wires. Repair or replace any damaged components.
  5. Test Power Supply and Ground: Ensure that the heater control circuit is receiving proper power and ground. Use a multimeter to check for voltage at the sensor’s connector. Repair any issues in the power supply or ground circuits.
  6. Check for ECU Issues: Although rare, inspect the ECU for any potential faults that could cause incorrect interpretation of the heater control circuit. Reprogram or replace the ECU if necessary.
  7. Clear Codes and Perform Test Drive: After completing the repairs, clear the trouble codes from the vehicle’s memory using the diagnostic scanner. Perform a test drive to ensure the vehicle operates properly and that the P0063 code does not return.


Understanding and addressing DTC P0063 is essential for maintaining optimal engine performance and emissions control. By following these detailed diagnostic and repair procedures, you can effectively address the P0063 trouble code, ensuring the vehicle’s HO2S heater control circuit operates correctly. Regular maintenance and careful inspection of the oxygen sensor and its electrical components can help prevent this code from appearing. If you found this guide helpful, please share it with fellow automotive enthusiasts and technicians. For more detailed guides and tips on car maintenance and repair, visit our website.