P2244: O2 Sensor Reference Voltage Performance Bank 1 Sensor 1
What to do
Expect worse economy and slightly reduced power. If an oxygen sensor was fitted recently, check that it is the exact part for this engine — a sensor that fits but carries the wrong calibration is a leading cause of this code, and no amount of testing the wiring will find it. Otherwise, ask for the supply and its ground to be checked for resistance rather than just continuity; a reference that sags under load tests fine with a simple continuity check.
What this code means
The reference voltage is present but not what it should be — drifted, sagging under load, or not matching the calibration the module expects.
This is the variant most likely to be a wrong or mismatched sensor rather than a failure, for the reasons set out at P2243: a part that fits but carries a different calibration resistor produces a reference reading the module can see is inconsistent with what it was told to expect. If the sensor was replaced shortly before this code appeared, that is the first thing to examine, not the last.
Where the sensor is original, a reference that sags rather than fails outright usually means resistance somewhere in the supply or its ground — a corroded terminal, a poor module ground — rather than the sensor itself. The distinction matters because the two repairs have nothing in common.
Likely causes
Start here
- Incorrect oxygen sensor fitted · moderate
- High resistance in sensor wiring · moderate
- Poor module ground connection · moderate
Less common
- Faulty oxygen sensor · moderate
- Corroded or loose connector · easy
- Failed sensor reference voltage supply · moderate
Symptoms
Components involved
Information, not instruction
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