HO2S Heater Control Circuit High Bank 1 Sensor 3
What it means
P0044 means the ECM detected an abnormally high voltage in the heater control circuit of the bank 1, sensor 3 oxygen sensor — a third, downstream sensor used on some larger exhaust systems. The heater brings the sensor to operating temperature. A high-voltage fault usually points to a wiring short, a failed heater element, or a connector problem. The engine runs normally, but emissions monitoring is affected.
Can I keep driving? Safe to drive — the engine runs normally. This is an oxygen-sensor heater circuit fault, so expect a warning light and a possible failed emissions test until repaired.
Common symptoms
What you'll notice
- Check-engine light on
- Failed or incomplete emissions readiness / smog test
- Slightly reduced fuel economy
- Delayed closed-loop fuel control
Common causes
Most likely first
- Short to voltage in the oxygen-sensor heater control circuitLikely
- Failed oxygen-sensor heater element (bank 1 sensor 3)Common
- Corroded or damaged connector or wiring at the sensorCommon
- Failed engine control module heater driver (rare)Less often
How to diagnose & fix
Work through it in order
- Scan and confirm the code, then locate the bank 1 sensor 3 oxygen sensor (a third, downstream sensor on some exhausts).
- Inspect the connector and wiring for a short to voltage, chafing, or corrosion.
- Measure the sensor's heater resistance and compare against specification.
- Repair damaged wiring; replace the oxygen sensor if the heater element has failed.
- If wiring and sensor test good, check the ECM driver as a last resort.
FAQ
Quick answers
Is it safe to drive with P0044?+
Can I just clear P0044?+
Related codes
Often seen with P0044
Read & clear P0044 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.