P2218
NOx Sensor Heater Control Circuit/Open Bank 2
NOx sensor / emissions (SCR)
Generic OBD-II
Medium
What it means
P2218 means the ECM has detected an open in the heater control circuit of the bank 2 NOx sensor, part of the emissions/SCR system that monitors oxides of nitrogen in the exhaust. It typically shows up as a check-engine light, but on diesels an unresolved NOx sensor fault can eventually force a power derate, so it should be repaired before it escalates.
Medium
Can I keep driving? Usually drivable at first, but on diesels a persistent NOx-sensor fault can trigger reduced power (derate) and emissions warnings, so don't ignore it.
Common symptoms
What you'll notice
- Check-engine light on
- Often no immediate driving symptoms
- Possible emissions/SCR warning message
- Reduced power or derate if the fault persists (diesel)
Common causes
Most likely first
- Faulty NOx sensor (bank 2)Likely
- Open circuit in the NOx sensor heater control wiringCommon
- Poor or corroded connection at the NOx sensorCommon
- Faulty NOx sensor control moduleLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame and check for companion NOx codes (P2219, P2220, P2221, P2208).
- Inspect the bank 2 NOx sensor connector and harness for an open, corrosion, or heat damage.
- Test the heater control circuit for continuity and confirm the sensor gets power and ground.
- Verify the NOx sensor module is powered and communicating on the data bus.
- If the wiring and connection are good, replace the bank 2 NOx sensor and retest.
FAQ
Quick answers
Is it safe to drive with P2218?+
For short periods, usually. It is an emissions-monitoring fault, but on many diesels an unresolved NOx sensor fault can lead to a power derate, so have it repaired promptly.
Can I just clear P2218?+
It returns until the open in the heater control circuit or the sensor itself is repaired, since the module keeps monitoring it.
Related codes
Often seen with P2218
Read & clear P2218 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX