P2207 indicates the powertrain control module has detected above-normal voltage in the heater control circuit for the Bank 1 NOx sensor. The NOx sensor relies on an internal heater to reach operating temperature quickly, and a 'circuit high' reading most often points to a wiring short to voltage, a failing sensor, or a ground-side fault rather than the engine computer.
The NOx sensor's integrated heater element can develop an internal short or resistance fault that pushes circuit voltage above the PCM threshold, making the sensor itself the single most likely cause.
The heater control or power feed wire may be chafed, pinched, or melted and touching a higher-voltage source, causing the PCM to see an unexpectedly high signal.
Corroded, pushed-out, or backed-out terminals in the NOx sensor connector can alter resistance and voltage, producing a 'circuit high' fault.
A poor, loose, or open ground for the NOx sensor heater can raise the apparent circuit voltage and trigger this code even though the power side is normal.
Incorrect routing, splicing, or shielding during prior service can create intermittent or permanent high-voltage conditions in the NOx heater circuit.
Although often suggested, an actual PCM/ECM driver failure causing P2207 is uncommon and should only be considered after the sensor, wiring, connectors, and grounds have been ruled out.
Short trips are usually possible, but the vehicle may run an emissions-related derate or limp mode, will likely fail an emissions inspection, and should be diagnosed promptly to avoid catalyst or DPF complications.
No. PCM replacement is rarely the correct fix for this code. Most cases are resolved by replacing the NOx sensor or repairing the heater circuit wiring, connector, or ground.
NOx sensors are most common on diesel engines with selective catalytic reduction, but some gasoline direct-injection or lean-burn engines also use them; the diagnostic approach is the same.
The NOx sensing element must reach a high operating temperature to function accurately; the internal heater brings it up to temperature quickly so emissions control operates soon after a cold start.