What it means
The heater resistance of the Bank 1 Sensor 3 heated oxygen sensor is outside the expected range.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 3 is a heated oxygen sensor located after the first two sensors on the bank, where fitted. Its heater brings the sensing element up to temperature, and the control module checks the heater’s electrical resistance; this code sets when that resistance is outside the expected range.
Common causes
Most likely first.
- Oxygen-sensor heater element worn or out of specification
- Damaged heater wiring or connector
- Poor electrical connection
- Oxygen sensor failure
Symptoms
- Check-engine light on
- Oxygen-sensor heater may warm slowly
- Fuel economy may decrease
- Emissions may increase
How to diagnose it
- Use a scan tool to record freeze-frame data and check for related oxygen-sensor or heater codes that could point to a shared supply or wiring fault.
- Confirm the vehicle is equipped with a Bank 1 Sensor 3, then inspect that sensor’s connector and harness for heat damage, corrosion, loose pins, or chafing near the exhaust.
- With the sensor disconnected and the circuit safely isolated, measure the Bank 1 Sensor 3 heater resistance and compare it with the manufacturer's specification.
- Check the heater power and control wiring for continuity, shorts, and poor connections, following the wiring diagram for the vehicle.
- If wiring and connections pass, verify heater operation using the manufacturer's diagnostic procedure before replacing the sensor.
Common fixes
- Repair a loose, corroded, or heat-damaged Bank 1 Sensor 3 connector or wiring.
- Restore a poor heater-circuit connection or damaged terminal.
- Replace Bank 1 Sensor 3 if its heater resistance is outside the manufacturer's specification.
- Repair a confirmed heater-circuit wiring fault.
Can I keep driving?
Usually you can drive gently if the engine runs normally, but the sensor may warm slowly and emissions can rise. Arrange diagnosis soon, especially before an emissions test.
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.