Fault code P0559 – brake booster pressure sensor circuit intermittent/erratic

Fault code P0559 is called “Brake Booster Pressure Sensor Circuit Intermittent/Erratic” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0559

OBD-II error code P0559 is a generic code defined as “intermittent signal in brake booster pressure sensor circuit”. It is set when the powertrain control module (PCM) cannot receive a normal signal from the pressure sensor.

Fault code P0559 – brake booster pressure sensor circuit intermittent/erratic

The brake booster pressure sensor circuit is designed to monitor the amount of pressure applied to the brake booster. The circuit is controlled by the PCM to adapt to different braking situations and adjust the pressure and facilitate brake pedal operation.

This process is necessary for the correct and safe functioning of mechanical brakes. As well as slowing or stopping the vehicle with minimal foot pressure on the brake pedal.

If the PCM receives an intermittent signal from the brake booster pressure sensor, it will set code P0559. The warning lamp will then illuminate, which may require several failure cycles.

Symptoms of vehicle malfunctions

The main signal that an error P0559 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
  2. Increased force required to depress the brake pedal.
  3. The brake light may flash while braking.
  4. Absence of brake lights.

The P0559 error is quite serious, as it can cause problems with the brakes, which can be dangerous. The severity level will progress and may become a problem requiring immediate attention.

Factors that can cause this error code

The error code P0559 can mean that one or more of the following problems have occurred:

  • Faulty brake booster pressure sensor.
  • Worn or damaged vacuum lines.
  • Broken, damaged, corroded wiring harness.
  • Problem with connector or its contacts.
  • Faulty brake booster.
  • One-way vacuum brake booster valve has failed.
  • Sometimes the cause is a defective PCM module.

How to fix or reset OBD-2 code P0559

Some suggested steps for troubleshooting and fix the error code P0559:

  1. Check the brake booster pressure sensor.
  2. Test the pressure in the brake system.
  3. Inspect wires and connectors for damage.
  4. Inspect brake booster and one-way valve.
  5. If the error persists, check the PCM module.

Diagnose and repair of problems

When error P0559 occurs, the first step is to locate all components related to the brake booster pressure sensor circuit. These are the sensor itself, brake booster, vacuum lines, wiring, connectors and the PCM in the simplex system.

Once these components are found, a thorough visual inspection should be performed to check all associated wiring and connectors for obvious defects. Such as scratches, scuffs, exposed wires, or burn spots.

Connectors should also be checked for corrosion or damaged contacts. Vacuum lines should be checked for safety, cracks, leaks and general level of serviceability.

Checking the wiring

If the code remains, but there is no visible damage to the brake system wiring. Prepare to perform reference voltage, continuity, resistance, and ground tests on all associated wiring.

Be sure to disconnect the sensor from the PCM when testing the wiring to prevent damage to the controller. Compare all readings obtained with those in the manual, and if any abnormalities are found, repair or replace the wiring.

In addition to the wiring, test the pressure sensor itself, as it is part of the control circuit. Replace the sensor if its resistance differs from the value specified in the manual.

Most often the error P0559 is related to a failed brake booster pressure sensor, its replacement should solve the problem.

On which vehicles does this problem occur most frequently

Fault code P0559 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Acura
  • Alfa Romeo
  • BMW
  • Chevrolet (Cruze)
  • Citroen (C4, Picasso)
  • Dodge
  • Fiat
  • Ford
  • Hyundai
  • Mercedes-Benz
  • Nissan
  • Opel
  • Peugeot
  • Pontiac
  • Subaru

Fault code P0559 can sometimes be found with other errors. The most common are the following: P0555, P0556, P0557, P0558.


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