P0055
HO2S Heater Resistance Bank 1 Sensor 3
Emissions / O2 sensor
Generic OBD-II
Medium
What it means
P0055 means the heater element inside the Bank 1, Sensor 3 oxygen sensor is out of its expected resistance range — the heater that brings the sensor up to temperature is failing. Sensor 3 sits downstream in the exhaust, so this is an emissions-monitoring fault rather than a running problem.
Medium
Can I keep driving? Safe to drive — this is an emissions monitoring fault; the car runs normally but will show a check-engine light and may fail an emissions test.
Common symptoms
What you'll notice
- Check-engine light on
- Fails or is not ready for an emissions test
- Oxygen-sensor heater monitor won't complete
Common causes
Most likely first
- Failed oxygen-sensor heater element (most common — replace the sensor)Likely
- Corroded or damaged wiring/connector at the sensorCommon
- Blown fuse or bad relay feeding the heater circuitCommon
- ECM heater-driver fault (least likely)Less often
How to diagnose & fix
Work through it in order
- Check the fuse and relay for the O2 heater circuit.
- Inspect the Bank 1 Sensor 3 connector and wiring.
- Measure the sensor's heater resistance against spec.
- Replace the oxygen sensor if resistance is out of range; clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P0055?+
Yes — performance is unaffected. The main consequences are a check-engine light and a likely emissions-test failure until the sensor heater is fixed.
Can I just clear P0055?+
It'll return once the ECM checks heater resistance again. Replacing the sensor is usually what clears it for good.
Related codes
Often seen with P0055
Read & clear P0055 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX