Code
P1550
FORD
P — Powertrain
Power Steering Pressure Sensor Out of Self-Test Range
Views:
UK: 20
EN: 33
RU: 36
AI status
Completed
Completed
100%
Causes
- Failed or intermittent power steering pressure sensor
- Damaged wiring or poor connector contact in sensor circuit
- Short to battery or ground in sensor signal or reference circuit
- Low or contaminated power steering fluid (hydraulic systems)
- Mechanical steering pump failure or internal binding (hydraulic systems)
- Faulty power/ground or reference voltage from module
Symptoms
- EPAS/Power Steering warning lamp or generic warning on dash
- Reduced or loss of power steering assist, heavy steering
- Intermittent or erratic steering assist (varying effort)
- Steering pump noise or groaning (hydraulic systems)
- DTC P1550 stored and possibly related codes present
What to check
- Retrieve freeze frame and live data with a scan tool; observe pressure sensor PID and related PIDs during steering
- Visually inspect sensor, harness, and connector for damage, corrosion or loose pins
- Check power steering fluid level and condition (if hydraulic system)
- Backprobe sensor connector; measure reference voltage, signal voltage, and ground with key on
- Wiggle harness and connector while monitoring live data to find intermittent faults
- Scan for communications or module errors (U-codes) that could affect self-test
Signal parameters
- Reference voltage: typically 5.0 V (verify factory spec for vehicle)
- Sensor output: commonly around 0.5–4.5 V across pressure range (mid-range ~2.5 V at idle/no-load) — confirm Ford spec
- Signal response: voltage should change smoothly as steering load/pressure changes
- Self-test acceptance: sensor output must be within module-specified range and respond to applied load
Diagnostic algorithm
- Read and record DTCs, freeze frame and live PIDs with a capable scan tool. Note related codes and whether code is current or historic.
- Perform a visual inspection of the steering pressure sensor, connector and wiring harness for damage, corrosion, pin push-out, or fluid contamination.
- Check power steering fluid level and condition (for hydraulic systems). Top up or bleed per factory procedure if low or contaminated.
- Backprobe the sensor connector. With key on (engine off) confirm reference voltage (typically ~5 V), ground continuity and sensor signal voltage. Compare to factory values.
- Monitor sensor signal while turning steering wheel (or applying load). Voltage should vary smoothly; check for dropouts or stuck values.
- If reference or ground is missing or out of range, trace and repair open/short to PCM/steering module. Check connectors and splice points.
- If wiring and power/ground are good but sensor output is invalid, substitute a known-good sensor or bench-test sensor per service data.
- If sensor and wiring check OK, check module inputs, CAN communication, and available TSBs or calibrations. Reprogram or replace module only after eliminating wiring/sensor faults.
- After repairs, clear codes and perform self-test/road test to confirm proper operation and that code does not return.
Likely causes
- Corroded or loose sensor connector
- Open/short in signal wire between sensor and steering module/PCM
- Sensor out of calibration or failed electronics
- Low fluid level or air in hydraulic system causing abnormal pressure readings
- Intermittent module CAN/communication fault affecting self-test
Fault status
Status
Power steering pressure sensor output was outside the allowed range during the system self-test. Fault stored; steering assist may be reduced or disabled until issue is resolved.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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