P2246 is set when the Powertrain Control Module detects that the reference voltage supplied to the upstream (Bank 1, Sensor 1) oxygen sensor is higher than the expected range. This reference voltage is used by the sensor to generate its signal; an out‑of‑range high voltage usually points to a fault in the sensor itself, its wiring, or the PCM output.
The sensor's internal reference voltage regulator has failed, causing the reference line to read high. This is the most common cause of P2246.
Damage to the sensor harness (chaffing, rodent damage, heat exposure) can cause the reference wire to be pulled up to battery voltage or lose continuity, resulting in a high reading.
Poor contact in the sensor connector or the PCM side connector can introduce resistance or voltage offsets that appear as a high reference voltage.
A malfunction within the PCM's reference voltage driver circuit can produce an abnormally high voltage, though this is far less common than sensor or wiring issues.
Non‑OEM sensors, incorrect wiring splices, or sensor grounds that are not properly connected can cause the reference voltage to read outside specification.
No. The PCM is rarely the cause of this code. A failed sensor, wiring issue, or connector problem accounts for the majority of cases. PCM replacement should only be considered after those items have been verified as good.
You can drive the vehicle, but you may experience reduced fuel economy, rough idle, and increased emissions. Prolonged operation with a faulty O2 sensor can also lead to catalytic converter damage over time.
Clearing the code only turns off the check engine light; if the underlying fault remains, the code will return after the next drive cycle.