P0550 OBD Error Code: Problem & Solutions

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OBD II fault code P0550 is a generic code that is defined as “Power steering pressure (PSP) sensor/switch circuit malfunction”. This generic powertrain diagnostic trouble code (DTC) typically applies to all OBD-II vehicles equipped with a power steering pressure sensor. It indicates that PCM has detected a fault in the power steering pressure sensor circuit. This problem normally occurs more frequently at low vehicle speeds. This code is detected when there is an excessively low or high voltage from the power steering pressure sensor is sent to the PCM

P0550 is a diagnostic trouble code (DTC) for "Power Steering Pressure Sensor Circuit Malfunction". This code is set when PCM has failed to receive a voltage input signal from the power steering pressure sensor that is proportionate to the steering angle sensor input signal. The power steering pressure sensor (PSP) helps in smooth handling of the vehicle by telling the computer of your vehicle that how much force is required to turn the steering wheel at a certain angle. This signal works in conjunction with signals sent to the PCM by the steering angle sensor (SAS).

Code P0550 is set when the signal from PSP sensor and the signal from steering angle sensor don’t match at all. In that case power steering doesn’t know how much additional support to provide.

What causes this problem with the Power Steering Pressure Sensor Circuit Malfunction?

• Faulty PSP sensor
• Leakage of power steering fluid
• Defective power steering pump
• Open or shorted PSP sensor wiring
• Corroded or loose connectors
• ECM issue

1. Power steering pressure sensor - Power steering pressure (PSP) sensor here is the main cause for storing this trouble code. Faulty PSP sensor will always create wrong signals and need to be replaced as soon as possible.
2. Power steering pump - A power steering pump provides the required hydraulic pressure to steer your automobile with a minimal effort on the steering wheel. Make sure it is working efficiently to avoid the associated error codes.
3. Wiring and connectors - Always repair or replace the damaged and corroded wiring and connectors as these could also become the cause for storing this trouble code.
4. Power steering fluid - Power-steering fluid is the hydraulic fluid that transmits the power in power steering. 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. ECM - The Engine Control Module (also called the Powertrain Control Module or PCM) is the brains of the engine management system. It controls the fuel mixture, ignition timing, variable cam timing and emissions control.

Below mentioned are some common symptoms for the OBD II code which can actually help you to identify this code. Rectify this code as soon as you discover any of the following symptoms:

• Leakage of power steering fluid
• Engine stalling
• Difficulty to steer
• Extraordinary noises
• Erratic idle
• Reduced fuel efficiency
• Illuminated check engine light

Due to this trouble code most of the drivers face problem of hard steering and engine stalling which actually makes the driving challenging. This code has to be resolved as soon as it discovered if you want no problems in drivability. To fix this code following repair and replacements may help:

• Inspect the PSP sensor carefully and replace it if found faulty.
• Repair the source of leakage of power steering fluid.
• Replace the defective power steering pump.
• Check the wiring, circuits and connections, repair or replace the damaged ones.
• Replace the dirty power steering fluid.

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Here are some steps which you one follow in order to diagnose this fault code:

• Check your power steering fluid level and top up as necessary.
• Take a good look at the sensor itself as these sensors leak through the sensor itself, so make sure it's dry and there are no obvious signs of damage and/or leaks.
• To rule out the sensor, you will need to test it. Usually, the sensor itself is mounted to a power steering pressure line.
• 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.
• Fasten any loose lines, especially the one with the sensor mounted to it.
• Using multimeter, verify the integrity of the power steering pressure sensor circuit(s).

Common Mistakes When Diagnosing the P0550 Code

While diagnosing this code, it is always suggested to turn off the engine first, and let it cool down and always wear personal protective equipment for your safety. These systems use high pressures that could cause harm so be careful, pinhole leaks are dangerous and are a serious hazard. If you are not familiar with the dangers of working with hydraulic systems, please bring your vehicle to a reputable repair facility. People usually ignore these things and commit mistakes.