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Home / DTC / P0551 — Power Steering Pressure Sensor/Switch Circuit Range/Performance

P0551 — Power Steering Pressure Sensor/Switch Circuit Range/Performance

Detailed page for trouble code P0551.

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Code

P0551

Generic P — Powertrain

Power Steering Pressure Sensor/Switch Circuit Range/Performance

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short, or high resistance in sensor signal, reference or ground circuit
  • Faulty power steering pressure sensor or pressure switch
  • Corroded or damaged connector at the sensor
  • Blown fuse or loss of 5 V reference supply to the sensor
  • Poor PCM ground or internal PCM fault (less common)
  • Low power steering fluid, pump problems or mechanical blockage affecting pressure readings

Symptoms

  • Malfunction Indicator Lamp (MIL) / trouble code stored
  • Erratic idle or stalling in some cases (ECM uses pressure for load compensation)
  • Reduced engine power or torque management while steering
  • Possible increased steering effort or degraded steering assist (depending on system)
  • Intermittent or no change in steering assist when turning wheel

What to check

  • Read stored codes and freeze frame data with a scan tool; note engine speed, load and steering input at fault
  • Visually inspect sensor, connector and wiring for corrosion, pin damage, chafing or fluid contamination
  • Verify battery voltage and inspect related fuses and power distribution
  • Backprobe sensor connector to measure reference, signal and ground with key ON and engine running
  • Use a lab scope (preferred) or multimeter to observe signal behavior while turning the steering wheel (pressure changes should change voltage)
  • Wiggle test wiring and connector while monitoring signal for intermittent faults

Signal parameters

  • Reference supply: typically a regulated 5 V from the PCM (verify 4.8–5.2 V at sensor with key ON)
  • Signal output (analog pressure sensor): approx. 0.5–4.5 V proportional to steering hydraulic pressure (varies by manufacturer)
  • Switch output (if fitted): open/closed or low/high signal when pressure threshold is reached
  • Expected behavior: signal voltage should change smoothly with steering input; no sudden drops to 0 V or short to battery voltage
  • Typical continuity/impedance: low ohms to ground for ground circuit and stable resistance for signal circuit (manufacturer specs required for exact values)

Diagnostic algorithm

  1. Retrieve all codes and freeze frame data. Note conditions when P0551 set (engine temp, RPM, steering angle/input).
  2. Visually inspect the pressure sensor, harness, and connector for damage, contamination, or loose pins. Repair if found.
  3. With key ON (engine OFF), backprobe the sensor harness: verify 5 V reference present, good ground, and signal voltage within expected idle range.
  4. Start engine and monitor signal while turning steering lock-to-lock. Confirm signal changes smoothly with pressure. Use scope if available to view waveform.
  5. If signal is stuck high/low or erratic, unplug the sensor and re-check reference and ground at the harness connector to isolate wiring vs sensor.
  6. Perform continuity and resistance checks between sensor connector and PCM for reference, signal and ground to locate opens or shorts.
  7. Repair any damaged wiring, corroded connector, or poor ground. Replace sensor if wiring and supply checks are good but signal remains out of range.
  8. Clear codes and road-test under similar conditions that set the code. Re-scan and verify no return of P0551.
  9. If fault persists after sensor and wiring repair, consider PCM input circuit testing or replacement per manufacturer procedures.

Likely causes

  • Damaged wiring or connector to pressure sensor (most common)
  • Defective pressure sensor/switch
  • Missing or unstable 5 V reference or bad ground at sensor
  • Intermittent connector contact or water intrusion

Fault status

⚠️ Status
Power Steering Pressure Sensor/Switch Circuit Range/Performance. PCM detects signal voltage or switch state outside expected parameters — check sensor, wiring, power/ground, and steering hydraulic system.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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P0550 P0552 P0521 P0507
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Code

P0551

GWM P — Powertrain

- Invalid indicator / the pressure sensor in the power steering has not been adjusted

Brand: GWM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short, or high resistance in sensor signal, reference or ground circuit
  • Faulty power steering pressure sensor or pressure switch
  • Corroded or damaged connector at the sensor
  • Blown fuse or loss of 5 V reference supply to the sensor
  • Poor PCM ground or internal PCM fault (less common)
  • Low power steering fluid, pump problems or mechanical blockage affecting pressure readings

Symptoms

  • Malfunction Indicator Lamp (MIL) / trouble code stored
  • Erratic idle or stalling in some cases (ECM uses pressure for load compensation)
  • Reduced engine power or torque management while steering
  • Possible increased steering effort or degraded steering assist (depending on system)
  • Intermittent or no change in steering assist when turning wheel

What to check

  • Read stored codes and freeze frame data with a scan tool; note engine speed, load and steering input at fault
  • Visually inspect sensor, connector and wiring for corrosion, pin damage, chafing or fluid contamination
  • Verify battery voltage and inspect related fuses and power distribution
  • Backprobe sensor connector to measure reference, signal and ground with key ON and engine running
  • Use a lab scope (preferred) or multimeter to observe signal behavior while turning the steering wheel (pressure changes should change voltage)
  • Wiggle test wiring and connector while monitoring signal for intermittent faults

Signal parameters

  • Reference supply: typically a regulated 5 V from the PCM (verify 4.8–5.2 V at sensor with key ON)
  • Signal output (analog pressure sensor): approx. 0.5–4.5 V proportional to steering hydraulic pressure (varies by manufacturer)
  • Switch output (if fitted): open/closed or low/high signal when pressure threshold is reached
  • Expected behavior: signal voltage should change smoothly with steering input; no sudden drops to 0 V or short to battery voltage
  • Typical continuity/impedance: low ohms to ground for ground circuit and stable resistance for signal circuit (manufacturer specs required for exact values)

Diagnostic algorithm

  1. Retrieve all codes and freeze frame data. Note conditions when P0551 set (engine temp, RPM, steering angle/input).
  2. Visually inspect the pressure sensor, harness, and connector for damage, contamination, or loose pins. Repair if found.
  3. With key ON (engine OFF), backprobe the sensor harness: verify 5 V reference present, good ground, and signal voltage within expected idle range.
  4. Start engine and monitor signal while turning steering lock-to-lock. Confirm signal changes smoothly with pressure. Use scope if available to view waveform.
  5. If signal is stuck high/low or erratic, unplug the sensor and re-check reference and ground at the harness connector to isolate wiring vs sensor.
  6. Perform continuity and resistance checks between sensor connector and PCM for reference, signal and ground to locate opens or shorts.
  7. Repair any damaged wiring, corroded connector, or poor ground. Replace sensor if wiring and supply checks are good but signal remains out of range.
  8. Clear codes and road-test under similar conditions that set the code. Re-scan and verify no return of P0551.
  9. If fault persists after sensor and wiring repair, consider PCM input circuit testing or replacement per manufacturer procedures.

Likely causes

  • Damaged wiring or connector to pressure sensor (most common)
  • Defective pressure sensor/switch
  • Missing or unstable 5 V reference or bad ground at sensor
  • Intermittent connector contact or water intrusion

Fault status

⚠️ Status
Power Steering Pressure Sensor/Switch Circuit Range/Performance. PCM detects signal voltage or switch state outside expected parameters — check sensor, wiring, power/ground, and steering hydraulic system.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0550 P0552 P0521 P0507
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Code

P0551

HUMMER P — Powertrain

Power Steering Pressure Sensor Circuit Range/Performance

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short, or high resistance in sensor signal, reference or ground circuit
  • Faulty power steering pressure sensor or pressure switch
  • Corroded or damaged connector at the sensor
  • Blown fuse or loss of 5 V reference supply to the sensor
  • Poor PCM ground or internal PCM fault (less common)
  • Low power steering fluid, pump problems or mechanical blockage affecting pressure readings

Symptoms

  • Malfunction Indicator Lamp (MIL) / trouble code stored
  • Erratic idle or stalling in some cases (ECM uses pressure for load compensation)
  • Reduced engine power or torque management while steering
  • Possible increased steering effort or degraded steering assist (depending on system)
  • Intermittent or no change in steering assist when turning wheel

What to check

  • Read stored codes and freeze frame data with a scan tool; note engine speed, load and steering input at fault
  • Visually inspect sensor, connector and wiring for corrosion, pin damage, chafing or fluid contamination
  • Verify battery voltage and inspect related fuses and power distribution
  • Backprobe sensor connector to measure reference, signal and ground with key ON and engine running
  • Use a lab scope (preferred) or multimeter to observe signal behavior while turning the steering wheel (pressure changes should change voltage)
  • Wiggle test wiring and connector while monitoring signal for intermittent faults

Signal parameters

  • Reference supply: typically a regulated 5 V from the PCM (verify 4.8–5.2 V at sensor with key ON)
  • Signal output (analog pressure sensor): approx. 0.5–4.5 V proportional to steering hydraulic pressure (varies by manufacturer)
  • Switch output (if fitted): open/closed or low/high signal when pressure threshold is reached
  • Expected behavior: signal voltage should change smoothly with steering input; no sudden drops to 0 V or short to battery voltage
  • Typical continuity/impedance: low ohms to ground for ground circuit and stable resistance for signal circuit (manufacturer specs required for exact values)

Diagnostic algorithm

  1. Retrieve all codes and freeze frame data. Note conditions when P0551 set (engine temp, RPM, steering angle/input).
  2. Visually inspect the pressure sensor, harness, and connector for damage, contamination, or loose pins. Repair if found.
  3. With key ON (engine OFF), backprobe the sensor harness: verify 5 V reference present, good ground, and signal voltage within expected idle range.
  4. Start engine and monitor signal while turning steering lock-to-lock. Confirm signal changes smoothly with pressure. Use scope if available to view waveform.
  5. If signal is stuck high/low or erratic, unplug the sensor and re-check reference and ground at the harness connector to isolate wiring vs sensor.
  6. Perform continuity and resistance checks between sensor connector and PCM for reference, signal and ground to locate opens or shorts.
  7. Repair any damaged wiring, corroded connector, or poor ground. Replace sensor if wiring and supply checks are good but signal remains out of range.
  8. Clear codes and road-test under similar conditions that set the code. Re-scan and verify no return of P0551.
  9. If fault persists after sensor and wiring repair, consider PCM input circuit testing or replacement per manufacturer procedures.

Likely causes

  • Damaged wiring or connector to pressure sensor (most common)
  • Defective pressure sensor/switch
  • Missing or unstable 5 V reference or bad ground at sensor
  • Intermittent connector contact or water intrusion

Fault status

⚠️ Status
Power Steering Pressure Sensor/Switch Circuit Range/Performance. PCM detects signal voltage or switch state outside expected parameters — check sensor, wiring, power/ground, and steering hydraulic system.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0550 P0552 P0521 P0507
Repair manuals

Manual library for HUMMER

138

Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HUMMER

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Code

P0551

MERCEDES-BENZ P — Powertrain

Power Steering Pressure Sensor Circuit Range/Performance

Brand: MERCEDES-BENZ
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short, or high resistance in sensor signal, reference or ground circuit
  • Faulty power steering pressure sensor or pressure switch
  • Corroded or damaged connector at the sensor
  • Blown fuse or loss of 5 V reference supply to the sensor
  • Poor PCM ground or internal PCM fault (less common)
  • Low power steering fluid, pump problems or mechanical blockage affecting pressure readings

Symptoms

  • Malfunction Indicator Lamp (MIL) / trouble code stored
  • Erratic idle or stalling in some cases (ECM uses pressure for load compensation)
  • Reduced engine power or torque management while steering
  • Possible increased steering effort or degraded steering assist (depending on system)
  • Intermittent or no change in steering assist when turning wheel

What to check

  • Read stored codes and freeze frame data with a scan tool; note engine speed, load and steering input at fault
  • Visually inspect sensor, connector and wiring for corrosion, pin damage, chafing or fluid contamination
  • Verify battery voltage and inspect related fuses and power distribution
  • Backprobe sensor connector to measure reference, signal and ground with key ON and engine running
  • Use a lab scope (preferred) or multimeter to observe signal behavior while turning the steering wheel (pressure changes should change voltage)
  • Wiggle test wiring and connector while monitoring signal for intermittent faults

Signal parameters

  • Reference supply: typically a regulated 5 V from the PCM (verify 4.8–5.2 V at sensor with key ON)
  • Signal output (analog pressure sensor): approx. 0.5–4.5 V proportional to steering hydraulic pressure (varies by manufacturer)
  • Switch output (if fitted): open/closed or low/high signal when pressure threshold is reached
  • Expected behavior: signal voltage should change smoothly with steering input; no sudden drops to 0 V or short to battery voltage
  • Typical continuity/impedance: low ohms to ground for ground circuit and stable resistance for signal circuit (manufacturer specs required for exact values)

Diagnostic algorithm

  1. Retrieve all codes and freeze frame data. Note conditions when P0551 set (engine temp, RPM, steering angle/input).
  2. Visually inspect the pressure sensor, harness, and connector for damage, contamination, or loose pins. Repair if found.
  3. With key ON (engine OFF), backprobe the sensor harness: verify 5 V reference present, good ground, and signal voltage within expected idle range.
  4. Start engine and monitor signal while turning steering lock-to-lock. Confirm signal changes smoothly with pressure. Use scope if available to view waveform.
  5. If signal is stuck high/low or erratic, unplug the sensor and re-check reference and ground at the harness connector to isolate wiring vs sensor.
  6. Perform continuity and resistance checks between sensor connector and PCM for reference, signal and ground to locate opens or shorts.
  7. Repair any damaged wiring, corroded connector, or poor ground. Replace sensor if wiring and supply checks are good but signal remains out of range.
  8. Clear codes and road-test under similar conditions that set the code. Re-scan and verify no return of P0551.
  9. If fault persists after sensor and wiring repair, consider PCM input circuit testing or replacement per manufacturer procedures.

Likely causes

  • Damaged wiring or connector to pressure sensor (most common)
  • Defective pressure sensor/switch
  • Missing or unstable 5 V reference or bad ground at sensor
  • Intermittent connector contact or water intrusion

Fault status

⚠️ Status
Power Steering Pressure Sensor/Switch Circuit Range/Performance. PCM detects signal voltage or switch state outside expected parameters — check sensor, wiring, power/ground, and steering hydraulic system.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0550 P0552 P0521 P0507
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P0551

MITSUBISHI P — Powertrain

Power steering pressure switch

Brand: MITSUBISHI
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short, or high resistance in sensor signal, reference or ground circuit
  • Faulty power steering pressure sensor or pressure switch
  • Corroded or damaged connector at the sensor
  • Blown fuse or loss of 5 V reference supply to the sensor
  • Poor PCM ground or internal PCM fault (less common)
  • Low power steering fluid, pump problems or mechanical blockage affecting pressure readings

Symptoms

  • Malfunction Indicator Lamp (MIL) / trouble code stored
  • Erratic idle or stalling in some cases (ECM uses pressure for load compensation)
  • Reduced engine power or torque management while steering
  • Possible increased steering effort or degraded steering assist (depending on system)
  • Intermittent or no change in steering assist when turning wheel

What to check

  • Read stored codes and freeze frame data with a scan tool; note engine speed, load and steering input at fault
  • Visually inspect sensor, connector and wiring for corrosion, pin damage, chafing or fluid contamination
  • Verify battery voltage and inspect related fuses and power distribution
  • Backprobe sensor connector to measure reference, signal and ground with key ON and engine running
  • Use a lab scope (preferred) or multimeter to observe signal behavior while turning the steering wheel (pressure changes should change voltage)
  • Wiggle test wiring and connector while monitoring signal for intermittent faults

Signal parameters

  • Reference supply: typically a regulated 5 V from the PCM (verify 4.8–5.2 V at sensor with key ON)
  • Signal output (analog pressure sensor): approx. 0.5–4.5 V proportional to steering hydraulic pressure (varies by manufacturer)
  • Switch output (if fitted): open/closed or low/high signal when pressure threshold is reached
  • Expected behavior: signal voltage should change smoothly with steering input; no sudden drops to 0 V or short to battery voltage
  • Typical continuity/impedance: low ohms to ground for ground circuit and stable resistance for signal circuit (manufacturer specs required for exact values)

Diagnostic algorithm

  1. Retrieve all codes and freeze frame data. Note conditions when P0551 set (engine temp, RPM, steering angle/input).
  2. Visually inspect the pressure sensor, harness, and connector for damage, contamination, or loose pins. Repair if found.
  3. With key ON (engine OFF), backprobe the sensor harness: verify 5 V reference present, good ground, and signal voltage within expected idle range.
  4. Start engine and monitor signal while turning steering lock-to-lock. Confirm signal changes smoothly with pressure. Use scope if available to view waveform.
  5. If signal is stuck high/low or erratic, unplug the sensor and re-check reference and ground at the harness connector to isolate wiring vs sensor.
  6. Perform continuity and resistance checks between sensor connector and PCM for reference, signal and ground to locate opens or shorts.
  7. Repair any damaged wiring, corroded connector, or poor ground. Replace sensor if wiring and supply checks are good but signal remains out of range.
  8. Clear codes and road-test under similar conditions that set the code. Re-scan and verify no return of P0551.
  9. If fault persists after sensor and wiring repair, consider PCM input circuit testing or replacement per manufacturer procedures.

Likely causes

  • Damaged wiring or connector to pressure sensor (most common)
  • Defective pressure sensor/switch
  • Missing or unstable 5 V reference or bad ground at sensor
  • Intermittent connector contact or water intrusion

Fault status

⚠️ Status
Power Steering Pressure Sensor/Switch Circuit Range/Performance. PCM detects signal voltage or switch state outside expected parameters — check sensor, wiring, power/ground, and steering hydraulic system.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0550 P0552 P0521 P0507
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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