P2220 indicates the engine computer (PCM) has detected an abnormally high voltage or current in the NOx sensor heater control circuit for Bank 2. The NOx sensor heater is responsible for bringing the sensor to operating temperature quickly, and this code suggests an electrical fault in the heater circuit.
The heater element inside the NOx sensor may have an internal short, causing excessive current draw and triggering the high circuit voltage code.
Chafed, pinched, or corroded wiring in the heater circuit can cause a short to power, resulting in high voltage readings. Check connectors for bent pins or moisture intrusion.
A blown fuse or defective relay can cause voltage irregularities in the circuit, though this may also result in a low voltage code depending on the failure mode.
The PCM controls the heater circuit, and a shorted transistor or internal fault in the PCM driver could cause high voltage. This is uncommon and should only be considered after all other causes are ruled out.
While the vehicle may still be drivable, prolonged driving with this code can lead to increased emissions and potential damage to the NOx sensor or catalytic system. Address the issue promptly to avoid failing emissions tests or further complications.
No, the PCM is rarely the cause of P2220. The issue is almost always due to a faulty NOx sensor, wiring problem, or related component. PCM replacement should only be considered after all other potential causes have been thoroughly ruled out.
Replacing the NOx sensor may resolve the issue if the heater element is faulty. However, it is critical to first verify the cause through proper diagnosis, as wiring or connector issues are also common and may persist if not addressed.
The NOx sensor operates most accurately at high temperatures. The heater ensures the sensor reaches and maintains its optimal operating temperature quickly, even during cold starts, to provide accurate emissions readings and reduce harmful NOx output.