What it means
A fault has been detected in the heater sense circuit for the NOx sensor on Bank 1 Sensor 3.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The heater sense circuit reports heater-related feedback for the Bank 1 Sensor 3 NOx sensor to the control module. This code sets when that feedback circuit has a fault, such as an open or high-resistance wire, a poor connector, or a failed sensor heater sense circuit.
Common causes
Most likely first.
- Open or high resistance in the heater sense wire
- Loose, damaged, or corroded connector
- NOx sensor heater or internal sense circuit fault
- Fault in the heater control module or wiring
Symptoms
- Check engine light
- Possible NOx or aftertreatment warning
- Increased NOx emissions or failed emissions test
How to diagnose it
- Use a scan tool to review freeze-frame data, heater status, and related codes to identify when Bank 1 Sensor 3 heater feedback becomes faulty.
- Inspect the Sensor 3 connector for looseness, corrosion, damaged terminals, or a pin pushed back from its proper position.
- Trace the heater sense wire for breaks, chafing, or heat damage along the route from the sensor.
- Following the wiring diagram, test heater sense circuit continuity and resistance against the manufacturer's specification.
- If the wiring and connector pass, test the sensor's internal heater sense circuit and the heater control module as directed by the manufacturer.
Common fixes
- Repair an open or damaged heater sense wire.
- Clean or replace loose, corroded, or damaged connector terminals.
- Repair a high-resistance connection in the heater sense circuit.
- 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, restrict driving to necessary trips and get the heater sense fault checked soon. The module may not verify that the NOx sensor heater is working, which can compromise aftertreatment monitoring and 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.