What it means
The NOx sensor heater control circuit for Bank 1 Sensor 3 is reporting a high condition. This indicates an electrical fault in that circuit; it does not mean the engine’s lambda sensor or closed-loop fuel control is inactive.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The heater control circuit controls the heater that brings the Bank 1 Sensor 3 NOx sensor to operating temperature. This code sets when the heater control circuit is detected high, often because the control line is shorted to a supply or its wire is pinched against B+; it does not mean engine lambda control is inactive.
Common causes
Most likely first.
- Heater control line shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light
- Possible NOx or aftertreatment warning
- Increased NOx emissions or failed emissions test
How to diagnose it
- Review freeze-frame data and live heater status for Bank 1 Sensor 3 to confirm when the high condition is recorded.
- Inspect the heater harness for pinching, melted insulation, or contact with a battery-positive or other supply wire.
- Check the Sensor 3 heater connector for corrosion, displaced pins, or terminals that may bridge to a supply.
- Following the wiring diagram, test the heater control line for a short to supply and verify circuit continuity using the manufacturer's procedure.
- If the circuit checks out, test the Sensor 3 heater and control module for an internal fault.
Common fixes
- Reposition and secure pinched heater wiring away from supply wires and hot exhaust parts.
- Repair insulation damage or a heater control wire short to supply.
- Repair damaged or corroded connector terminals.
- Replace the Bank 1 Sensor 3 NOx sensor or heater control module if testing confirms an internal fault.
Can I keep driving?
If the vehicle runs normally, limit driving and arrange diagnosis soon. The heater may not operate as intended, leaving NOx readings unreliable and potentially increasing emissions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.