enbgde
P0559 Generic (SAE) Basic entry

Brake Booster Pressure Sensor Circuit Intermittent

Updated 2026-10-02 · Vehicle speed, idle control & auxiliary inputs

Severity
Medium
Typical repair cost
40 – 350 EUR
System
Powertrain

What it means

P0559 is stored when the Brake Booster Pressure signal drops out or jumps erratically for short periods. Intermittent faults are almost always connector, wiring or vibration related.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

Advertisement728 × 90

Symptoms

  • Check engine light on
  • Idle too high, too low or hunting
  • Stalling when coming to a stop
  • Speedometer or cruise control not working in some cases

Common causes

  1. Damaged, chafed or corroded wiring in the Brake Booster Pressure circuit
  2. Corroded, loose or water-damaged connector terminals
  3. Failed Brake Booster Pressure component (sensor, solenoid or actuator)
  4. Poor ground connection for the module or component
  5. Faulty control module driver (rare, confirm all else first)

How to diagnose

  1. Read freeze frame data and note when the code set (cold start, under load, after rain)
  2. Inspect the Brake Booster Pressure connector for bent pins, corrosion and water; wiggle the harness with the engine running and watch live data
  3. Measure supply voltage and ground at the connector with the key on
  4. Check the signal wire for shorts to ground or battery and for continuity to the control module
  5. Test or substitute the Brake Booster Pressure only after wiring and connectors are confirmed good
  6. Clear the code and complete a drive cycle to confirm the repair

Frequently asked questions

Can I keep driving with P0559?

Usually yes for a short time, but expect reduced performance or higher fuel use. Have it diagnosed within a few days.

Will clearing P0559 fix it?

No. Clearing only erases the stored code; it returns as soon as the monitor runs again unless the cause is repaired.

Related codes

P0556P0557P0558

Nearby codes in this group