The code P0042: HO2S Heater Control Circuit (Bank 1 Sensor 3) indicates a malfunction in the heater control circuit of the oxygen sensor located in Bank 1 Sensor 3. This issue can lead to inefficient engine operation and increased emissions, often caused by a faulty sensor heater, wiring issues, or an ECM malfunction.
The heater element of the oxygen sensor has a malfunction in its control circuit.
P0042 quick overview
| Meaning | P0042: HO2S Heater Control Circuit (Bank 1 Sensor 3) |
| Is it serious? | Moderately. It can affect fuel efficiency and emissions. |
| Possible causes | – Faulty oxygen sensor heater – Open or short in the heater circuit wiring – Poor electrical connection in the heater circuit – Faulty Engine Control Module (ECM) |
| How to diagnose? | Scan for Codes: Confirm P0042 with an OBD-II scanner. Visual Inspection: Check the wiring and connectors for damage. Circuit Testing: Use a multimeter to test the heater circuit for continuity. Sensor Testing: Check the resistance of the oxygen sensor heater. ECM Testing: If necessary, test the ECM outputs to the heater circuit. |
| What is Bank 1 Sensor 3? | This is 3rd sensor from the engine to the exhaust for engine head 1. Read the full Bank1 vs Bank2 explanation. |
Test oxygen sensor PDF
- How to locate a specific sensor (bank1, 2)
- How to test with a multimeter
- How to test using an OBD-II reader
- Verify O2 sensor/CAT just with live data
How to diagnose P0042
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Advice | Description of Diagnostic Step |
|---|---|
| Scan for Additional Codes | Use an OBD-II scanner to check for additional codes that might provide more insight into the underlying issue. |
| Visual Inspection | Inspect the oxygen sensor and its wiring for any visible signs of damage, corrosion, or disconnection. |
| Check for Exhaust Leaks | Inspect the exhaust system for leaks, as they can affect the oxygen sensor’s readings. |
| Test the Heater Circuit | Use a multimeter to test the heater circuit for continuity, shorts, and proper resistance. |
| Measure Sensor Voltage/Signal | Check the oxygen sensor’s output voltage or signal to ensure it’s within the expected range. |
| Evaluate Electrical Connections | Ensure all electrical connections related to the oxygen sensor are secure and free of corrosion. |
| Test the Sensor’s Response Time | Use a scan tool to monitor the oxygen sensor’s response time to changes in the fuel mixture. |
| Check the ECM’s Outputs | If necessary, test the Engine Control Module’s (ECM) outputs to the oxygen sensor to ensure proper communication. |
| Replace Faulty Components | If a faulty oxygen sensor or damaged wiring is identified, replace the necessary components. |
| Clear Codes and Test Drive | After repairs, clear the codes with an OBD-II scanner and take the vehicle for a test drive to ensure the issue is resolved. |
Test oxygen sensor PDF
- How to locate a specific sensor (bank1, 2)
- How to test with a multimeter
- How to test using an OBD-II reader
- Verify O2 sensor/CAT just with live data
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko