NOx Sensor Heater Control Circuit/Open Bank 1
The NOx sensor heater control circuit on Bank 1 is open or not functioning properly. The ECM detected an electrical fault in the heater circuit that warms the NOx sensor for proper emissions monitoring.
What You Might Notice
- Check Engine Light (CEL) illuminated
- Failed emissions test
- Intermittent CEL flashing
- Reduced fuel economy
- Rough idle or slight hesitation
Most Common Causes
- 1
Open or broken heater wire
The wiring harness to the NOx sensor heater has broken, disconnected, or corroded, preventing current flow to the heating element.
- 2
Faulty NOx sensor heater element
The internal heating element inside the NOx sensor has failed or burned out, breaking the circuit.
- 3
Bad ECM/PCM relay or fuse
The relay or fuse controlling the NOx heater circuit is blown or failed, cutting power to the heater.
- 4
Corroded connector or terminals
Oxidation or corrosion at the NOx sensor connector or ECM connector prevents proper electrical contact.
How to Diagnose It
- 1
Check Open or broken heater wire — The wiring harness to the NOx sensor heater has broken, disconnected, or corroded, preventing current flow to the heating element.
- 2
Check Faulty NOx sensor heater element — The internal heating element inside the NOx sensor has failed or burned out, breaking the circuit.
- 3
Check Bad ECM/PCM relay or fuse — The relay or fuse controlling the NOx heater circuit is blown or failed, cutting power to the heater.
- 4
Check Corroded connector or terminals — Oxidation or corrosion at the NOx sensor connector or ECM connector prevents proper electrical contact.
How to Fix It
- 1
Inspect and replace NOx sensor heater wiring
Locate the heater circuit wiring harness to the Bank 1 NOx sensor. Check for breaks, corrosion, or disconnections. Repair or replace the wiring as needed.
- 2
Replace NOx sensor
If the heater element inside the sensor is damaged, the entire NOx sensor must be replaced. Remove the old sensor and install a new OEM or quality replacement.
- 3
Check and replace relay or fuse
Examine the NOx heater relay and fuse in the engine bay fuse box. Test continuity; replace if faulty or blown.
- 4
Clean connectors and terminals
Disconnect the NOx sensor and ECM connectors. Clean all terminals with electrical contact cleaner and dielectric grease. Reconnect firmly to ensure good contact.
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