OBD-II code P0553 indicates that the Powertrain Control Module (PCM) has detected a high voltage condition in the power steering pressure sensor/switch circuit. This sensor monitors hydraulic pressure in the power steering system to help the PCM adjust engine idle speed during high-load maneuvers. A high circuit voltage typically points to a short to voltage, an open circuit, or a faulty sensor.
The sensor itself may be internally shorted or have failed, causing it to output a constant high voltage signal to the PCM.
The signal wire between the sensor and PCM may be shorted to a power source, such as a 5V reference or battery voltage, pulling the signal high.
A broken wire or poor connection in the ground or signal return path can cause the PCM to see a high voltage on the signal line.
Moisture, dirt, or physical damage at the sensor connector can create high resistance or a short to voltage, leading to an incorrect high signal.
An internal failure in the PCM is possible but should only be considered after all other causes have been thoroughly ruled out.
Yes, the vehicle is usually drivable, but you may experience erratic idle or stalling when turning the steering wheel, especially at low speeds. Exercise caution.
No, the PCM is very rarely the cause. The problem is almost always a faulty sensor, wiring issue, or poor connection. Replacing the PCM without proper diagnosis is a costly mistake.
It detects when power steering pressure is high (e.g., during parking) and sends a signal to the PCM so it can increase idle speed to prevent the engine from stalling.
Not directly, but a failing pump could produce abnormal pressure that might affect the sensor reading. However, the sensor or circuit is far more likely to be the cause.