P2220NOx Sensor Heater Control Circuit High (Bank 2)
The Bank 2 NOx sensor heater control circuit is stuck at a high voltage, typically from a short to power or a failed heater driver.
Definition
The control module switches the Bank 2 NOx sensor heater and monitors the control circuit's voltage state as feedback. P2220 sets when the circuit reads high when it should be pulled low, indicating a short to battery voltage, an open on the switched side, or a failed driver stage in the sensor's integrated module. Heater regulation is lost, so the sensor either overheats or never produces valid NOx data; the MIL illuminates, monitors stay incomplete, and diesel SCR systems can progress toward inducement derate.
Common causes
- Heater control wire shorted to battery voltage
- Failed heater driver inside the NOx sensor module
- Open control circuit reading pull-up voltage
- Heat-damaged or chafed harness near the exhaust
- Corroded connector terminals
Common misdiagnoses
- SCR catalyst
- DEF injector
- ECM/PCM replaced when the short is in the harness
- Charging system
Troubleshooting steps
1.Confirm the fault is hard or intermittent
Clear the code and recheck; an immediate reset indicates a hard short to trace, while an intermittent points to wiggle-testing the harness.
2.Inspect the Bank 2 sensor harness
Check routing near exhaust heat shields and adjacent powered circuits for melted or rubbed-through insulation.
3.Test the control circuit voltage
With the sensor disconnected and key on, constant battery voltage on the control circuit confirms a short to power in the harness.
4.Check connector integrity
Verify terminal tension and look for corrosion at the sensor module connector and any inline connectors.
5.Replace the NOx sensor if the harness is clean
An internal driver failure is common; install an OE sensor and confirm normal heater duty and current on the scan tool.