P0551 Power Steering Pressure Sensor Circuit Range/Performance
OBD-II Trouble Code Technical Description
Power Steering Pressure Sensor Circuit Range/Performance
What does that mean?
This generic powertrain diagnostic trouble code (DTC) typically applies to all OBD-II vehicles equipped with a power steering pressure sensor. That may include but is not limited to vehicles from Infiniti, Nissan, Toyota, Lexus, Mazda, Dodge, Chrysler, Jeep, Kia, etc.
Before hydraulically and electrically assisted steering systems were invented, manufacturers used an unassisted rack and pinion steering system. This made steering at low speed extremely difficult and inefficient.
For this reason we invented the power steering system. Generally speaking, a hydraulically assisted system will include 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 adjust accordingly.
The ECM illuminates the check engine light with P0551 and associated codes when it recognizes one or multiples condition outside a specific desired range within the power steering pressure sensors's circuit. Most times, I would say, this code is thrown by the ECM because of an electrical issue but at times, mechanical problems could possibly be the cause.
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. 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 most likely, your power steering system could completely fail and you could still drive your car, severity here is set to low. Obviously, that's a dumb idea, any issue left long enough will 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 P0551 diagnostic code may include:
Erratic idle Engine stalling symptoms Intermittent assist when steering (choppy turning) Hard to steer vehicle Whining noises Leaking fluid Poor handlingWhat are some of the common causes of the code?
Causes for this code may include:
Broken or damaged wiring harness Power steering fluid leak Fuse/relay defective Power steering pressure sensor defective ECM issue Pin/connector problem. (e.g. corrosion, melting, broken lock tab, etc.)What are some P0551 troubleshooting steps?
Be sure to check for technical service bulletins (TSBs) for your vehicle. Getting access to a known fix can save you time and money during diagnosis.
Tools
Some of the things you may need when diagnosing or repairing the power steering circuits and systems:
OBD code reader Power steering fluid Drain pan Multimeter Basic socket set Basic ratchet and wrench sets Basic screwdriver set Battery terminal cleaner Service manualSafety Tips
Let engine cool Chalk wheels Wear PPE (Personal protective equipment)NOTE: ALWAYS verify and record the integrity of your battery and charging system before further troubleshooting.
Basic Step #1
Always keep it simple at first. Check your power steering fluid level and top up as necessary. Check your parking space, any signs of a leak? If so, investigate further. If the fluid is low, it's going somewhere so make sure to repair any mechanical leaks before proceeding to any electrical diagnosing. Take a good look at the sensor itself, I've personally seen these sensors leak through the sensor itself, so make sure it's dry and there is no obvious signs of damage and/or leaks.
NOTE: These systems use high pressures that could cause harm so be c
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