P2212
NOx Sensor Heater Sense Circuit Intermittent Bank 1 Sensor 1
Auxiliary emissions control
Generic OBD-II
Medium
What it means
P2212 means the ECM saw an intermittent signal on the heater sense circuit of the bank 1, sensor 1 NOx sensor. The heater brings the sensor to operating temperature so it can read nitrogen-oxide levels accurately. An intermittent fault points strongly at a loose connector or chafed wiring rather than a constant failure. The engine keeps running, but emissions monitoring is affected and the fault should be traced down.
Medium
Can I keep driving? Usually driveable — this is an emissions-monitoring fault — but it will fail emissions and some diesels may derate, so have it repaired.
Common symptoms
What you'll notice
- Check-engine light on
- Intermittent NOx sensor readiness / emissions-test failure
- Possible SCR/DEF warning on diesels
- Often no obvious drivability change
Common causes
Most likely first
- Loose, corroded, or poor connector at the NOx sensor (typical with an intermittent fault)Likely
- Chafed or intermittently open/shorted wiring in the heater sense circuitCommon
- Faulty NOx sensor heater element (bank 1, sensor 1)Common
- Faulty NOx sensor control module — rareLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data, then wiggle-test the NOx sensor connector and harness while watching for the signal to drop out.
- Inspect the connector and pins for corrosion, spread terminals, or a loose fit; reseat or repair as needed.
- Check the heater sense circuit wiring for chafing and intermittent opens/shorts.
- Replace the NOx sensor if the heater sense signal stays intermittent with confirmed-good wiring.
FAQ
Quick answers
Is it safe to drive with P2212?+
Generally yes, since it's an emissions-monitoring fault, but the sensor's heater must work for proper NOx readings, and some diesels derate — so repair it rather than leaving it.
Can I just clear P2212?+
Because the fault is intermittent it will return when the connection drops out again. The loose connector or chafed wire needs to be found and fixed.
Related codes
Often seen with P2212
Read & clear P2212 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