The P2208 code indicates that the engine control module has detected an abnormal voltage or resistance in the heater sense circuit of the NOx sensor located on bank 1, sensor 1. This circuit monitors the heater element that brings the NOx sensor up to operating temperature; a fault here can prevent the sensor from reaching proper temperature and affect its readings.
The internal heater of the NOx sensor can open or short, causing the heater sense circuit to read out of range.
Corrosion, chafed wires, loose pins, or water intrusion can create an open or short in the sense circuit.
If the fuse supplying power to the heater sense circuit is open or the relay sticks, the ECM will see an abnormal voltage.
A high‑resistance ground can skew the sense voltage and trigger the code.
Though uncommon, a failure in the ECM’s sensor driver circuit can produce false readings; this is considered only after wiring and sensor checks.
Rarely, a calibration error can cause the ECM to misinterpret normal sensor heater voltage; a reflash may resolve it.
No. The PCM/ECM is rarely the cause; most P2208 faults are due to the NOx sensor heater, its wiring, fuse, relay, or ground. Only after those items are verified good should an ECM issue be considered.
You can drive short distances, but the NOx sensor may not reach proper temperature, leading to increased emissions and possible limp‑mode activation. It is advisable to diagnose and repair the fault promptly to avoid emissions test failure.
Clearing the code only removes the stored fault; if the underlying heater sense circuit problem remains, the code will return after the next drive cycle.
Often the heater element inside the NOx sensor fails, which requires sensor replacement because the heater is not serviceable separately. However, wiring or connector issues are also common and should be checked first.