P2223NOx Sensor Heater Sense Circuit Low (Bank 2)
The Bank 2 NOx sensor heater sense circuit is stuck at a low voltage, usually from a short to ground or an open feedback wire.
Definition
The control module reads a heater sense (feedback) circuit to confirm the Bank 2 NOx sensor heater is drawing current and holding the element at operating temperature. P2223 sets when that feedback stays below the plausible minimum, pointing to a short to ground, an open sense wire, or a failed feedback stage inside the sensor module. With heater performance unverified, Bank 2 NOx data is discarded, the MIL illuminates, and the NOx and SCR readiness monitors remain incomplete — failing emissions testing and risking SCR inducement measures on diesels.
Common causes
- Heater sense wire shorted to ground
- Open feedback circuit from broken wiring or a backed-out terminal
- Failed NOx sensor internal feedback circuitry
- Connector corrosion or water intrusion
- Harness chafe against the frame or exhaust shielding
Common misdiagnoses
- SCR catalyst
- DEF doser
- Bank 1 NOx sensor
- Vehicle grounds overhauled without testing the specific circuit
Troubleshooting steps
1.Scan for companion codes
Heater control codes set alongside suggest a shared supply or ground fault; an isolated P2223 targets the sense line specifically.
2.Check the sense wire for a short to ground
With both ends disconnected, verify no continuity between the feedback wire and chassis ground.
3.Verify sense circuit continuity
Measure the wire end to end; more than about 1 ohm or an open reading calls for a harness repair.
4.Inspect the sensor module connector
Underbody-mounted sensor modules commonly suffer moisture intrusion; look for corrosion and spread terminals.
5.Replace the NOx sensor if the circuit is intact
A good harness with no feedback signal means the sensor's internal monitoring circuit failed; fit an OE sensor and confirm monitor readiness.