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P0559 is a diagnostic trouble code (DTC) for "Brake Booster Pressure Sensor Circuit Intermittent". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0559 trouble code detects an issue with the brake booster pressure sensor circuit.
The P0559 code is a generic OBD-II trouble code that signifies a problem with the brake booster pressure sensor. The vehicle relies on the brake booster pressure system to aid braking, and the pressure sensor sends voltage input signal readings to the powertrain control module (PCM). When the voltage input signals do not match the rate of deceleration for the vehicle, then the P0559 code will be detected.
Some potential causes of the P0559 code include:
The P0559 trouble code will usually be accompanied by the check engine soon Warning Light illuminating on the instrument cluster. Usually the brake pedal will become harder and more resistant, though it is possible for there to be no noticeable drivability symptoms.
The P0559 code should be diagnosed using a standard OBD-II trouble code scanner. A trained mechanic can use the scanner to look at the freeze frame data to assess the code, and to look for any additional trouble codes that may be present. The codes should then be reset, and the vehicle restarted. If the trouble code does not return, it was likely stored erroneously, or it may be an intermittent issue.
If the P0449 trouble code remains on, then the technician should visually inspect the brake booster electrical components. All wires and connectors should be inspected, and any that are loose, corroded, or damaged should be replaced. In addition to the wires, the power steering fluid levels should be checked.
Next, the mechanic will inspect the brake booster system, and will check the sensors, hoses, and valves, to see if any defective components can be spotted. All defective components should be replaced, not repaired.
Each time a something is found and replaced, the codes should be reset, and the vehicle restarted. That way the mechanic will know exactly when the issue has been resolved. Once the code has gone away, the technician should take the vehicle for a short test drive to make sure that the brakes feel normal.
The most common mistake made when diagnosing the P0559 trouble code comes from not properly following the OBD-II trouble code diagnosis protocol. It is imperative that mechanics follow the protocol step by step, to ensure an efficient and thorough inspection and repair.
Brake boosters are frequently replaced when the P0559 trouble code is detected. However, total brake booster failure is very uncommon, and usually the issue is merely a single component within the system.
A vehicle with a detected P0559 code is still drivable. However, the brakes will likely be harder to deploy, which can make driving more dangerous, and the brake system may not work as efficiently and effectively as possible. As brakes are the most important safety feature in a vehicle, the P0559 code should be addressed immediately.
Some of the repairs for the P0559 code are:
In some vehicles, the P0559 will only be detected when the issue has happened during multiple ignition cycles. If this is the case, then it may appear as a “pending code” after the first instance.
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