Guide To P0551 OBD Error Code Solutions

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Are you confronting problems like vehicle performance, decrease in fuel economy, power steering fluid leaks or erratic idles then do not ignore it as these are the symptoms of OBD II Code P0551? Diagnostic trouble code P0551 means that power steering pressure sensor circuit range/performance is compromised or malfunctioning. P0551 Power Steering Pressure Sensor Circuit Range/Performance code is set when the ECM/PCM monitors a condition outside specific parameters within the sensor’s circuit.

OBD-II Code P0551 is defined as a Power Steering Pressure Sensor Circuit Range/Performance. This generic powertrain diagnostic trouble code (DTC) typically applies to all OBD-II vehicles equipped with a power steering pressure sensor. The Engine Control Module (ECM) or Powertrain Control Module (PCM) works in conjunction with the power steering pressure sensor to monitor the pressure within the system and adjust accordingly. The purpose of the Power Steering Pressure Sensor is to alert the PCM that the engine idle speed needs to be held at a specified level while the driver is operating the Power Steering System at slow vehicle speeds.

P0551 is set when PCM is not seeing the specified electrical change from the Power Steering Pressure Sensor whenever the Steering Angle Sensor shows angle change at slow speeds.

What causes this problem with the Power Steering Pressure Sensor Circuit Range/Performance?

• Faulty power steering pressure sensor
• Damaged or corroded wiring or connector
• Dirty power steering fluid
• Leakage of power steering fluid
• Faulty ECM

1. ECM - An engine control unit, also commonly called an engine control module, is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. If it is malfunctioned can lead to various problems so make sure you repair or replace it as required to avoid any more issues.
2. Power Steering Pressure Sensor - It’s clear with the description that this code is related to power steering pressure sensor. The purpose of the Power Steering Pressure Sensor is to alert the PCM that the engine idle speed needs to be held at a specified level while the driver is operating the Power Steering System at slow vehicle speeds. Power steering pressure (PSP) sensor should work efficiently to avoid all the associated trouble codes.
3. Power Steering Pump - A power steering pump is a part of the steering system that makes it easier to turn the steering wheel. Replace it if you find it faulty because an inoperative or defective power steering pump can make your drivability difficult.
4. Power Steering Fluid - Power steering fluid should not be dirty and its level should be up to the mark. Always top up the level of power steering fluid if you find its level low and replace the burnt and dirty one to avoid related trouble codes.
5. Connectors - Connectors are one of the smallest parts which adjoins power steering pump to hoses, if they are loose or broken then it may cause damage to the related parts. Inspect the related connector carefully as it should not be loose, broken or corroded. If you discover it defective or damaged, replace it in no time.

Some common symptoms for the trouble code P0551 are listed below. If you discover any of them do not ignore and take your vehicle to a reputed repair facility to avoid major expenses.

• Engine stalling
• Power steering fluid leak
• Trouble in steering
• Erratic idle
• Decreased engine performance
• Low vehicle performance
• Illuminated check engine light

Any trouble code stored for a long period can lead to major issues like expensive and major replacements and can lead to serious damage to your vehicle. So, it is always recommended to resolve them as soon as you discover them. To fix this error code P0551 following repair and replacements may help:

• Check out carefully the power steering pressure sensor and replace it if discovered faulty.
• Change the dirty power steering fluid.
• Inspect the corresponding wiring and look for loose or corroded connector, repair or replace them as required.
• Repair or replace the power steering system and related circuits.

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To fix this code a thorough diagnosis is required and to diagnose this code we always recommend you to seek a help of experienced diagnostician. Steps to diagnose this error code are as follows:

• Verify and record the integrity of your battery and charging system before further troubleshooting.
• Check your parking space, any signs of a leak? If so, investigate further.
• Check your power steering fluid level and top up as necessary.
• To rule out the sensor, you will need to test it. Most times these are hard aluminium/braided rubber lines and can be accessed from under the hood.
• Locate the electrical connector on the pressure sensor. Inspect for any oil residue/soaking. If the connector is soaked in oil, obviously the leak is a problem but the oil must be cleaned before reconnecting. A connector showing signs of melting and/or corrosion must be repaired.
• Check for physical damage. If the lines aren't fastened properly, the sensor may be rubbing on something and over time could cause an electrical problem of some sort.
• Verify the integrity of the power steering pressure sensor circuit(s).

Common Mistakes When Diagnosing the P0551 Code

Due to this code, one of the issues you might face is engine stalling at low speed and because of engine stalling people usually blame the idle air control system for the issue where in the actual cause is something else.