P0038: O2 Sensor Heater Control Circuit High — Bank 1 Sensor 2
What to do
No driveability impact. Fix before an emissions test.
What this code means
Voltage on the downstream bank 1 sensor heater circuit is above the expected range. An open circuit reads high, and on underfloor sensors an open circuit is frequently a connector that has corroded until its pins no longer make contact — worth cleaning and testing before the sensor is condemned.
Likely causes
Start here
- Corroded or loose connector · easy
- Open circuit in heater wiring · moderate
- Failed oxygen sensor heater element · easy
Less common
- Wiring shorted to voltage · moderate
- Road damage to underfloor wiring · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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