P0550
Power Steering Pressure Sensor Circuit Malfunction
When a vehicle powertrain module registers the fault code P0550, it points directly to an internal system malfunction identified as "Power Steering Pressure Sensor Circuit Malfunction". Operating your engine under this condition may degrade long-term fuel maps.
Driver's Summary
Your vehicle's computer logged P0550 after detecting a malfunction in the power steering pressure sensor circuit malfunction system. In practice, this fault causes engine stalls when turning at low speeds, rough idle when turning wheel. The vehicle is usually drivable, but the root cause needs attention soon to avoid more expensive repairs down the road.
Symptoms
Engine stalls when turning at low speeds, rough idle when turning wheel
Common Causes
- Defective Power Steering Pressure (PSP) sensor
- Low power steering fluid
- Damaged wiring harness
- Bad steering pump
How to Fix
- 1 Replace PSP sensor
- 2 Top off power steering fluid
- 3 Repair damaged wiring
- 4 Replace power steering pump
Technical Explanation
The ECM detects code P0550 by continuously monitoring the relevant sensor circuit against calibrated threshold values stored in its non-volatile memory. The control module samples the circuit continuously during normal operation, using both voltage level monitoring and frequency analysis to detect open circuits, shorts to ground, shorts to battery voltage, and high-resistance connections. The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
While the vehicle is typically drivable with P0550 active, avoid towing, aggressive acceleration, or extended highway driving until the fault is resolved. The primary risk is accelerated wear on defective power steering pressure (psp) sensor and low power steering fluid.
Mechanic's Pro Tip
Before replacing any component on P0550, spend 5 minutes inspecting the wiring harness and connector first — corrosion, chafed insulation, and backed-out pins cause the majority of these faults and cost nothing to fix. Use a multimeter to measure voltage drop across the connector pins under load; anything above 0.1V indicates excessive resistance that will cause intermittent failures even after replacing the sensor.
Fluid top-off: $20; PSP Sensor: $100 - $200