Power Steering Pressure Switch
A sensor that monitors power steering fluid pressure and signals the ECU to increase engine idle speed during tight turns.
The power steering pressure switch is a small sensor mounted in the high-pressure line of the power steering system. When a driver turns the steering wheel sharply (such as during parallel parking), the power steering pump must work harder, generating high hydraulic pressure. This extra load puts a mechanical drag on the engine, which can cause the engine RPM to drop or stall, especially at idle.
The pressure switch detects this pressure increase and sends a signal to the Engine Control Unit (ECU). The ECU then makes minor adjustments to fuel injection and the idle air control system, slightly increasing engine idle speed to compensate for the load and prevent stalling.
If the power steering pressure switch fails, the engine may stall or shudder when turning the wheel at low speeds. A failed switch can also leak power steering fluid through its electrical connector.