What it means
NOx Sensor Heater Sense Circuit High (Bank 2): the signal voltage is above the expected range. The NOx sensor heater brings the sensor to operating temperature; a fault delays accurate NOx readings used for SCR control.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The Bank 2 NOx sensor heater brings the sensor up to operating temperature so it can report exhaust NOx for SCR emissions control. The control module monitors the heater sense signal and sets P2224 when it rises above the expected range, potentially delaying accurate NOx readings.
Common causes
Most likely first.
- Open signal line
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Record freeze-frame data and scan Bank 2 NOx sensor and heater readings to see when the high signal is detected.
- Inspect the Bank 2 sensor connector and harness for corrosion, loose terminals, opens, or a wire pinched against a power source.
- Using the vehicle wiring information, check the heater sense line for an open and check for an unintended connection to battery supply.
- Check continuity and terminal contact through the Bank 2 heater sense circuit, paying attention to corrosion or pin damage.
- If the circuit checks out, test the Bank 2 NOx sensor heater and sense output according to the manufacturer's procedure.
Common fixes
- Clean and secure corroded or loose Bank 2 NOx sensor connector pins.
- Repair an open in the Bank 2 heater sense signal wire.
- Repair wiring pinched or shorted to a power source and protect its routing.
- Replace a damaged connector or terminal that cannot maintain contact.
- Replace the Bank 2 NOx sensor assembly if its heater sense output fails testing.
Can I keep driving?
Cautious driving is usually possible if the vehicle behaves normally, but get the emissions fault diagnosed soon. NOx and SCR control may be impaired, and an AdBlue/DEF warning can progress to a no-start countdown if ignored.
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.