Technical Description of OBD-II Trouble Code
Malfunction in the Circuit of the Power Steering Pressure Sensor
What does that signify?
This generic diagnostic trouble code (DTC) for powertrain typically applies to all OBD-II vehicles that are equipped with a power steering pressure sensor. This includes vehicles from Infiniti, Nissan, Toyota, Lexus, Mazda, Dodge, Chrysler, Jeep, Kia, etc.
Before the invention of hydraulically and electrically assisted steering systems, manufacturers used an unassisted rack and pinion steering system. This made steering at low speeds extremely difficult and inefficient.
For this reason, the power steering system was invented. Generally, a hydraulically assisted system includes a belt-driven power steering pump, steering rack/box, and various hoses/lines and sensors. 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 make adjustments accordingly.
The ECM illuminates the check engine light with the code P0550 and associated codes when it detects one or multiple conditions outside of a specific desired range within the power steering pressure sensor’s circuit. Most of the time, this code is thrown by the ECM due to an electrical issue, but mechanical problems could also be the cause.
The P0550 Power Steering Pressure Sensor Circuit Malfunction code is set when the ECM/PCM detects a general malfunction within the sensor’s circuit. It is one of five related codes, which are P0550, P0551, P0552, P0553, and P0554.
What is the severity of this DTC?
Given the fact that it is likely that your power steering system could completely fail and you could still drive your car, the severity of this issue is considered low. However, it is important to note that leaving any issue unresolved for a long time will ultimately cost you more in the long run.
An example of a power steering fluid pressure switch/sensor:
What are some of the symptoms of the code?
Symptoms of a P0550 diagnostic code may include:
What are some of the common causes of the code?
Causes for this code may include:
What are some P0550 troubleshooting steps?
Be sure to check for technical service bulletins (TSBs) for your vehicle. Accessing a known fix can save you time and money during the diagnosis process.
Tools
Some of the tools you may need when diagnosing or repairing the power steering circuits and systems include:
Safety Tips
NOTE: ALWAYS verify and record the integrity of your battery and charging system before further troubleshooting.
Basic Step #1
Always start with the simplest steps. Check your power steering fluid level and top up as necessary. Check your parking space for any signs of a leak. If there is a leak, further investigation is required. If the fluid is low, it is going somewhere, so make sure to repair any mechanical leaks before proceeding with electrical diagnosis. Inspect the sensor itself for any signs of leakage, ensuring that it is dry and there are no obvious signs of damage or leaks.
NOTE: These systems use high pressures that can be dangerous, so exercise caution. Pinhole leaks are hazardous and pose a serious risk. If you are not familiar with the dangers of working with hydraulic systems, it is recommended to bring your vehicle to a reputable repair facility.
Basic Step #2
To rule out the sensor as the cause, you will need to test it. Refer to your service manual for the required specifications. Usually, the sensor is mounted to a power steering pressure line. In most cases, these lines are made of hard aluminum or braided rubber and can be accessed from under the hood.
NOTE: A common leak is found where the rubber meets the hard pressure line, as it can separate and cause a difficult-to-find leak.
Basic Tip #3
Locate the electrical connector on the pressure sensor and inspect it for any oil residue or soaking. If the connector is soaked in oil, the leak is obviously a problem, but the oil must be cleaned before reconnecting. If the connector shows signs of melting or corrosion, it must be repaired.
NOTE: Make sure to disconnect the battery before performing any electrical repairs.
Basic Step #4
Check for any physical damage. In this case, the sensor is exposed to harsh conditions. If the lines are not fastened properly, the sensor may be rubbing against something and could eventually cause an electrical problem. Fasten any loose lines, especially the one with the sensor mounted to it.
Basic Step #5
You may be able to verify the integrity of the power steering pressure sensor circuit(s). To rule out any problems with your wiring harness, you could disconnect the circuit at the sensor and the ECM. Using a multimeter, refer to your service manual and verify that all the desired values are within the specified range. If everything appears to be fine up to this point, it is recommended to bring the vehicle to a reputable repair facility.
