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
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