P2253 indicates that the powertrain control module (PCM) has detected a higher-than-expected voltage on the negative current control circuit of the upstream oxygen (O2) sensor on bank 1, sensor 1. This usually points to an electrical fault in the sensor itself or its wiring, causing the PCM to interpret the sensor signal as out of range.
The sensor's internal circuitry can develop a short to voltage or an open circuit, causing the PCM to read a high voltage on the negative current control line.
Damaged insulation or chafed wires in the sensor harness can allow battery voltage to contact the negative control circuit, triggering the high‑voltage condition.
Moisture, dirt, or loose pins at the sensor connector can increase resistance or create intermittent shorts, leading to erroneous high voltage readings.
Although less common, a short to ground can also cause the PCM to interpret the circuit as high due to the way it monitors voltage levels.
A malfunction inside the PCM's O2 sensor driver circuit is possible but rare; it should be considered only after all wiring and sensor checks have been ruled out.
No. The PCM is rarely the cause; most P2253 cases are due to a faulty O2 sensor, wiring short, or connector issue. Replacing the PCM without first checking those components usually does not resolve the code.
Yes. A malfunctioning upstream O2 sensor can lead to incorrect fuel‑trim calculations, resulting in poor fuel economy, rough idle, hesitation, or increased emissions.
Only the indicated sensor (bank 1, sensor 1) needs to be tested and possibly replaced. The downstream sensor is monitored separately and does not normally cause P2253.