NOx Sensor Heater Circuit High Bank 2
The P2224 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the heater circuit of the nitrogen oxide (NOx) sensor on Bank 2. The NOx sensor heater is essential for quickly bringing the sensor to operating temperature to accurately measure NOx emissions. A high voltage reading suggests a short to power, a faulty sensor, or a wiring issue. This code is common in diesel vehicles with selective catalytic reduction (SCR) systems.
1. Most Common Causes
- Short circuit in the heater sense circuit wiring to battery positive voltage (B+)
- Internally damaged NOx sensor with a fault in the heater sense circuit
- Corroded, loose, or moisture-contaminated NOx sensor connector or terminals
- Excessive resistance in the wiring due to poor connections
- Internal ECM failure in the NOx sensor monitoring circuit
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Increased NOx emissions
- Possible failed emissions test
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the NOx sensor connector and wiring for damage, corrosion, or shorts.
Step 3: Measure voltage at the heater circuit; compare to manufacturer specs (typically 12V with key on).
Step 4: Test the NOx sensor heater resistance; replace if out of range.
Step 5: Clear code and test drive; if code returns, replace the NOx sensor.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but the vehicle may enter limp mode and fail emissions. Prolonged driving could damage the SCR system.
How much does it cost to fix?▼
Typically $200-$600 including parts and labor. The NOx sensor itself costs $150-$400, plus diagnostic time.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.