What it means
The control module detects an open or faulty control circuit for the bank 1 sensor 2 NOx sensor heater. The code does not by itself identify the failed component.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
A heater in the bank 1 sensor 2 NOx sensor warms the sensing element so it can operate under the exhaust system's conditions. The control module monitors the heater control circuit and sets this code when it detects an open or faulty circuit, which can involve the heater winding, connector, wiring, or control electronics.
Common causes
Most likely first.
- Heater winding open
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Review freeze-frame and related sensor codes to see whether the heater fault occurs during cold starts or persists after warm-up.
- Inspect the bank 1 sensor 2 heater connector for a pushed-back pin, corrosion, heat damage, or a loose fit.
- Check the heater harness for breaks, chafing, or damage near the exhaust and sensor.
- Test heater circuit continuity and supply/control paths against the wiring diagram and manufacturer's specification.
- If the wiring and connector are intact, test the sensor heater and relevant control electronics using the manufacturer's procedure.
Common fixes
- Restore a pushed-back terminal or repair a poor heater connector.
- Repair an open or damaged heater circuit wire.
- Replace the sensor if its heater winding is open.
- Repair the control module circuit only if testing confirms an internal fault.
Can I keep driving?
Cautious driving is generally possible if the engine runs normally, but the sensor may take longer to operate and NOx emissions monitoring can be impaired. Repair it promptly if a DEF warning or start countdown appears.
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.