What it means
The control module detects a fault in the bank 1 sensor 2 NOx sensor heater sense circuit. The code alone does not identify the cause.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 2 is the downstream NOx sensor after the engine’s first cylinder bank; its heater warms the sensing element so it can measure NOx correctly. The control module monitors a separate heater sense circuit to check heater operation, and this code sets when that circuit has a fault without specifying whether the cause is the sensor, wiring, power, or ground.
Common causes
Most likely first.
- Failed NOx sensor heater or heater sense element
- Open or short in heater sense wiring
- Corroded or loose sensor connector
- Power or ground fault in the heater circuit
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
- Record freeze-frame data and check for other NOx sensor or heater codes to see whether the fault is isolated to Bank 1 Sensor 2.
- With the exhaust cool, inspect the sensor connector and harness for corrosion, looseness, damaged pins, heat damage, or chafing.
- Check the specified heater power and ground connections for an open, poor connection, or unintended short using the wiring diagram.
- Test continuity and isolation of the Bank 1 Sensor 2 heater sense wire between its connector and the module, following the manufacturer's procedure.
- If wiring and power or ground are sound, test the heater and sense element as specified before replacing the sensor.
Common fixes
- Repair a loose or corroded Bank 1 Sensor 2 connector or terminal.
- Repair an open or shorted heater sense wire or damaged harness section.
- Restore a faulty heater power or ground connection.
- Replace the Bank 1 Sensor 2 NOx sensor if its heater or sense element fails the specified tests.
Can I keep driving?
If there are no drivability problems, a short drive for diagnosis is generally reasonable, but do not leave the fault unresolved. The NOx or AdBlue/DEF warning may progress to a no-start countdown, and emissions compliance may be affected.
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.