What it means
NOx Sensor Heater Control Circuit/Open (Bank 2): the control circuit is open. The NOx sensor heater brings the sensor to operating temperature; a fault delays accurate NOx readings used for SCR control.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The heater in the bank 2 NOx sensor warms its sensing element so the emissions system can receive usable readings. P2218 sets when the module detects an open heater control circuit, interrupting the path that supplies or controls heater current.
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
- Save freeze-frame data and check live bank 2 sensor heater status to confirm the heater is not operating as expected.
- With the exhaust cool, inspect the bank 2 sensor connector for a loose plug, pushed-back pin, corrosion, or heat damage.
- Trace the heater control wiring for a break, melted insulation, or chafing near the exhaust.
- Test heater circuit continuity, power, and ground using the wiring diagram and compare results with the manufacturer's specification.
- If the external circuit is intact, test the bank 2 sensor heater and module-side control circuit using the manufacturer's procedure.
Common fixes
- Reconnect or repair a loose or damaged bank 2 sensor heater connector.
- Repair an open or heat-damaged heater control wire.
- Restore a poor heater power or ground connection.
- Replace the bank 2 NOx sensor if its heater winding is open.
- Repair a confirmed open in the module-side heater control circuit.
Can I keep driving?
A short drive may be possible if the vehicle runs normally, but the bank 2 sensor may not warm up and NOx readings may remain unreliable. Avoid extended driving because emissions faults can prompt an AdBlue/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.