P2244 indicates that the engine control module has detected an abnormal reference voltage for the upstream oxygen sensor on bank 1. The reference voltage powers the sensor’s internal circuitry; when it falls outside the calibrated range the ECM stores this code.
The sensor’s internal reference‑voltage circuit can fail, causing the ECM to read an out‑of‑range voltage.
Open circuits, shorts to ground, or high resistance in the reference‑voltage line will alter the voltage seen by the ECM.
A wiring fault that pulls the reference line toward battery voltage or ground will trigger the code.
The ECM’s internal driver that supplies the reference voltage may be degraded, though this is less common than sensor or wiring issues.
A complete ECM malfunction can cause erroneous reference‑voltage readings, but this is rare and should be considered only after all other causes are ruled out.
No. The PCM is rarely the root cause; most often the fault lies in the sensor itself or its wiring.
A poor ground on the sensor or ECM can affect the reference voltage, but the code specifically points to the reference‑voltage line rather than the ground circuit.
Only after confirming the sensor or its circuit is faulty; a thorough voltage and resistance check should precede replacement.
Clearing the code will turn off the light temporarily, but the underlying fault will cause the code to return until the root cause is repaired.