Faulty power steering pressure sensor or switch; Damaged, corroded, or disconnected wiring or connector at the sensor; Open or shorted circuit in the signal or ground wire between the sensor and PCM; Low power steering fluid level or contaminated fluid affecting hydraulic pressure; Failed power steering pump not building sufficient pressure; PCM internal fault or software issue misinterpreting the signal

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0550

P0550Power Steering Pressure Sensor/Switch Circuit

Q: What does code P0550 mean?

Power Steering Pressure Sensor/Switch Circuit. P0550 indicates that the powertrain control module (PCM) has detected an abnormal signal from the power steering pressure sensor or switch circuit. The computer expects a specific voltage or switch state that changes with steering load, and it has seen a value outside the acceptable range for a calibrated time.

P0550 indicates that the powertrain control module (PCM) has detected an abnormal signal from the power steering pressure sensor or switch circuit. The computer expects a specific voltage or switch state that changes with steering load, and it has seen a value outside the acceptable range for a calibrated time.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the check engine light or a dedicated power steering warning light
Heavier than normal steering effort, especially at low speeds or during parking maneuvers
A whining or groaning noise from the power steering pump when turning the wheel
Intermittent steering assist that feels normal one moment and stiff the next
Often no symptoms besides the warning light, with steering feel unchanged

Common causes, most likely first

Faulty power steering pressure sensor or switch
Damaged, corroded, or disconnected wiring or connector at the sensor
Open or shorted circuit in the signal or ground wire between the sensor and PCM
Low power steering fluid level or contaminated fluid affecting hydraulic pressure
Failed power steering pump not building sufficient pressure
PCM internal fault or software issue misinterpreting the signal

How to diagnose and fix it

Check power steering fluid level and condition, topping off or flushing as needed
Inspect the sensor connector and wiring for corrosion, chafing, or loose pins
Measure sensor reference voltage and signal voltage with a multimeter, comparing to manufacturer specifications
Test the sensor resistance or switch continuity through its operating range
Check for continuity and shorts in the signal and ground circuits between sensor and PCM
Replace the power steering pressure sensor or switch if testing confirms it is faulty
Clear the code and verify the repair with a test drive, confirming the light stays off

What the pressure sensor code hides

A low fluid level or a failing pump can set P0550 without any electrical fault, so always verify hydraulic pressure before condemning the sensor.
Some vehicles use a simple on/off switch rather than an analog pressure sensor, and the code can set if the switch sticks or the idle-up signal is lost.
The PCM may use the pressure signal to adjust idle speed and engine load, so a faulty circuit can cause idle fluctuations or stalling that owners misattribute to the engine.
Corroded pins inside the connector are a frequent cause that visual inspection alone misses; a wiggle test with the scanner live data can expose an intermittent signal.
Replacing the sensor without checking the ground circuit often leads to a repeat code, because a poor ground skews the signal voltage.

Can I keep driving with P0550?

You can usually drive with P0550, but expect heavier steering effort and avoid high-speed maneuvers or parking situations that demand quick steering response. If the steering becomes very stiff or the pump makes loud noises, stop driving and have the system inspected promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.