What it means
Voltage on the intake air O2 sensor heater control line on bank 1 is below the expected window. Wire shorted to ground or heater element shorted.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The heater control circuit supplies and regulates the heater inside the Bank 1 intake-air oxygen sensor. This code sets when voltage on that heater control line is below its expected range, indicating a possible short to ground, shorted heater, or poor connector contact.
Common causes
Most likely first.
- Heater wire shorted to ground
- Heater element shorted
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on after several drive cycles
- Slightly increased fuel consumption during cold start
- Delayed entry into closed-loop fuel control
- Failed emissions inspection (lambda readiness)
How to diagnose it
- Use freeze-frame data and heater status to confirm the low-voltage fault occurred while the Bank 1 heater was commanded on.
- Inspect the Bank 1 heater wiring for crushed or rubbed insulation that could expose the conductor to ground.
- Check the sensor connector for corrosion, moisture, loose terminals, or heat damage that could affect the heater circuit.
- Using the wiring diagram, test the heater control line for a short to ground and inspect power and ground paths against the manufacturer's procedure.
- If the harness and connections pass, test the Bank 1 heater element for a short before replacing the sensor.
Common fixes
- Repair Bank 1 heater wiring shorted to ground.
- Clean or replace damaged Bank 1 heater connector terminals.
- Repair a faulty heater supply or ground connection identified by circuit testing.
- Replace the Bank 1 intake-air oxygen sensor if its heater element is shorted.
Can I keep driving?
You can usually drive if the engine runs normally, but cold-start fuel use may increase and mixture control may take longer to begin. The heater fault can leave the oxygen-sensor readiness monitor incomplete and lead to an emissions inspection failure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.