Heated Oxygen Sensor Heater Control Circuit (Bank 1, Sensor 3)
The P0042 code means the vehicle's onboard diagnostic system has detected: Heated Oxygen Sensor Heater Control Circuit (Bank 1, Sensor 3). This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $300 (parts and labor)
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What Are the Symptoms of P0042?
- Check Engine Light on
- Slightly reduced fuel economy
- Extended warm-up time for sensor readings
- Possible emissions test failure
What Causes P0042? (Most Likely First)
- Faulty O2 sensor heater element in Sensor 3 Very High
- Blown fuse for O2 sensor heater circuit High
- Open or short in heater circuit wiring Moderate
- ECM/PCM heater control driver failure Low
Can I Still Drive with P0042?
Yes, but fix soon. P0042 is rated low severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
Frequently Asked Questions
What does P0042 mean?
P0042 indicates a malfunction in the heater control circuit for the Bank 1 Sensor 3 oxygen sensor, which is typically located after the catalytic converter.
Where is Bank 1 Sensor 3?
Bank 1 Sensor 3 is the oxygen sensor positioned after the second catalytic converter on Bank 1. Not all vehicles have a Sensor 3, so this code is most common on V6 or V8 engines.
Can I drive with P0042?
Yes, you can drive normally. The heater circuit issue mainly affects cold-start emissions performance and may cause a slight decrease in fuel economy.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P0042?
-
Confirm P0042 with scan tool and identify Bank 1 Sensor 3 location
-
Check the O2 sensor heater fuse in the fuse box
-
Measure heater circuit resistance at the sensor connector
-
Inspect wiring from ECM to the sensor for opens or shorts
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Which Vehicles Commonly Get P0042?
- 2008-2017 Honda Accord V6
- 2010-2019 Toyota Highlander V6
- 2007-2016 Lexus ES350
- 2009-2018 Nissan Murano
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