What it means
The heater control loop for the NOx sensor at bank 1 sensor 1 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 bank 1 sensor 1 NOx sensor has a heater control loop that the control module monitors for current draw and response. P220E sets when the loop's behavior falls outside its expected range or performance, which can point to a deteriorating heater, sensor, or connection.
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
- Review freeze-frame data and live warm-up data to see when bank 1 sensor 1 heater response falls outside its expected behavior.
- Inspect the bank 1 sensor 1 connector, wiring, and mounting for looseness, corrosion, heat damage, or movement that could affect the connection.
- Check the heater fuse, supply, and ground, and compare commanded heater operation with scan-tool feedback.
- Test heater circuit continuity and element behavior using the manufacturer's procedure and specification, watching for intermittent readings.
- If the circuit is sound, follow the manufacturer's checks to determine whether the bank 1 sensor 1 heater or sensor electronics have aged out of range.
Common fixes
- Secure the bank 1 sensor 1 connector or mounting if loose.
- Repair damaged or intermittent heater wiring.
- Replace a faulty fuse or restore a poor power or ground connection found in testing.
- Replace the bank 1 sensor 1 NOx sensor if its heater response fails specified tests.
- Repair the control module only if its heater command is confirmed faulty.
Can I keep driving?
You may be able to drive, but the bank 1 sensor 1 heater may respond too slowly or inconsistently for dependable NOx readings, risking emissions problems and inspection failure. Do not ignore a DEF warning or start countdown.
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.