NOx Sensor Heater Sense Circuit Bank 2
P2221 indicates the NOx sensor heater sense circuit on Bank 2 is not functioning properly. The engine control module monitors this heater circuit to ensure the NOx sensor operates at the correct temperature for accurate emissions measurements.
What You Might Notice
- Check engine light illuminated
- Reduced fuel economy
- Engine stalling or hesitation
- Failed emissions test
- Rough idle
Most Common Causes
- 1
Defective NOx sensor heater
The heater element within the NOx sensor on Bank 2 has failed or degraded, preventing proper sensor operation and temperature regulation.
- 2
Wiring or connector issue
Corroded, loose, or damaged wiring and connectors in the NOx sensor heater circuit disrupt the electrical signal to the ECM.
- 3
Engine control module malfunction
The ECM may have a fault in the circuit that controls or monitors the NOx sensor heater, preventing proper voltage or signal detection.
- 4
Blown fuse or relay failure
A failed fuse or relay in the NOx sensor heater circuit prevents power from reaching the sensor heater element.
How to Diagnose It
- 1
Check Defective NOx sensor heater — The heater element within the NOx sensor on Bank 2 has failed or degraded, preventing proper sensor operation and temperature regulation.
- 2
Check Wiring or connector issue — Corroded, loose, or damaged wiring and connectors in the NOx sensor heater circuit disrupt the electrical signal to the ECM.
- 3
Check Engine control module malfunction — The ECM may have a fault in the circuit that controls or monitors the NOx sensor heater, preventing proper voltage or signal detection.
- 4
Check Blown fuse or relay failure — A failed fuse or relay in the NOx sensor heater circuit prevents power from reaching the sensor heater element.
How to Fix It
- 1
Replace NOx sensor Bank 2
Remove and install a new NOx sensor on Bank 2. This is the most common fix for heater sense circuit faults and restores proper emissions monitoring.
- 2
Inspect and repair wiring harness
Visually inspect the NOx sensor heater wiring and connectors for corrosion, damage, or loose connections. Repair or replace damaged sections and reseat all connectors.
- 4
Reprogram or replace ECM
If wiring and sensor are confirmed good, have the ECM scanned for internal faults. Reprogram or replace the module if necessary to restore proper heater circuit control.
Need a deeper diagnosis?
Search for related repair guides or browse by system.