NOx Sensor Heater Control Circuit/Open Bank 2
The P2218 code indicates a problem with the heater circuit of the NOx sensor on Bank 2 (the side of the engine opposite cylinder #1). The NOx sensor measures nitrogen oxide levels in the exhaust to help the diesel particulate filter and selective catalytic reduction system function properly. The heater element is essential for the sensor to reach operating temperature quickly, especially during cold starts. An open circuit means there is a break in the electrical path, preventing the heater from working. This can be caused by a faulty sensor, damaged wiring, or a blown fuse.
01. Most Common Causes
- Faulty NOx sensor (Bank 2)
- Open or shorted wiring in the heater circuit
- Blown fuse or relay for the NOx sensor heater
- Corroded or loose connector at the sensor
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Increased emissions
- Possible reduced fuel economy
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Connect an OBD2 scanner and confirm code P2218. Check for other related codes.
Step 2: Visually inspect the NOx sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Use a multimeter to test the heater circuit resistance at the sensor connector (typically 2-10 ohms). If open, replace the sensor.
Step 4: Check the fuse and relay for the NOx sensor heater circuit. Replace if blown.
Step 5: If wiring and fuses are good, replace the NOx sensor on Bank 2.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but the vehicle may fail emissions and the NOx sensor is critical for proper diesel exhaust aftertreatment. Prolonged driving could lead to further issues or reduced performance.
How much does it cost to fix?▼
The cost typically ranges from $200 to $600, including parts and labor. The NOx sensor itself costs $150-$400, and labor adds $50-$200 depending on the vehicle.