What it means
The heater control loop for the NOx sensor at bank 1 sensor 2 reports off-spec behaviour — heater current draw or response time outside the calibrated range. NOx sensors only operate above ~600 °C, so heater control is critical.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The NOx sensor heater at bank 1 sensor 2 warms the sensing element so it can report accurately to the emissions control system. The module monitors heater current and warm-up response, and sets P220F when those readings are outside the expected performance range.
Common causes
Most likely first.
- Heater element ageing
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
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 live data for bank 1 sensor 2 heater status and warm-up response to see when performance falls out of range.
- With the exhaust cool, inspect the bank 1 sensor 2 mounting and its connector for looseness, corrosion, heat damage, or poor pin contact.
- Trace the sensor's wiring for chafing, melted insulation, or strain that could affect heater operation or sensor response.
- Compare heater current and response during a cold start with the manufacturer's specification and with the other bank's sensor where applicable.
- If wiring and mounting are sound, test the heater element and sensor response using the manufacturer's procedure to determine whether the sensor has aged.
Common fixes
- Repair poor connector contact or damaged wiring at bank 1 sensor 2.
- Secure the sensor mounting if it is loose.
- Replace the bank 1 sensor 2 NOx sensor if its heater or response is outside specification.
- Repair a confirmed heater control fault in the module circuit.
Can I keep driving?
You may be able to drive briefly if the vehicle runs normally, but avoid unnecessary trips because inaccurate NOx readings can cause emissions failure or trigger an AdBlue/DEF warning and eventual start restriction. Stop if a countdown or drivability warning 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.