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DTC codes / C05xx · Brakes, steering and suspension / C0567

C0567Brake Booster Solenoid Circuit Low

C0567 indicates that the antilock brake system (ABS) control module has detected a low-voltage condition on the electrical circuit that powers the brake booster solenoid. The solenoid is an electrically controlled valve that helps modulate vacuum or hydraulic assist to the brake booster, and a low circuit reading means the module sees less voltage or current than expected when the circuit is commanded on. This can disable the brake assist feature and trigger the ABS warning light.

SystemChassis
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaBrakes, steering and suspension

Symptoms you may notice

  • Illumination of the ABS warning light and possibly the traction control or stability control warning light
  • Often no symptoms besides the warning light, especially if the brake booster solenoid is not actively needed during normal driving
  • A hard or stiff brake pedal with increased effort required to stop the vehicle
  • Reduced or inconsistent brake assist, particularly during emergency braking or when the pedal is pressed quickly
  • A faint click or no click from the brake booster solenoid area when the ignition is turned on or the brake pedal is pressed
  • In some cases, the vehicle may enter a reduced-power or limp mode if the ABS module disables related functions

Common causes, most likely first

  1. A faulty brake booster solenoid with an open or high-resistance internal coil
  2. Damaged, corroded, or disconnected wiring or connector at the brake booster solenoid
  3. A blown fuse or poor connection in the power supply circuit to the solenoid
  4. High resistance in the ground circuit for the brake booster solenoid
  5. A failed ABS control module driver circuit that cannot supply proper voltage or current
  6. Water intrusion or contamination in the solenoid connector causing low voltage
  7. Aftermarket or incorrect replacement solenoid with wrong resistance specification

How to diagnose and fix it

  1. Verify the battery voltage and charging system are within specification, as low system voltage can set this code falsely
  2. Inspect the brake booster solenoid connector and wiring for corrosion, damage, or loose pins, and repair as needed
  3. Check the fuse and relay that supply power to the brake booster solenoid circuit
  4. Measure resistance across the brake booster solenoid coil and compare to the manufacturer's specification
  5. With the ignition on, back-probe the solenoid connector to check for battery voltage on the power side and good ground on the control side
  6. If voltage is low at the solenoid but the module commands it on, check the control circuit from the ABS module for opens or high resistance
  7. Replace the brake booster solenoid if it fails electrical testing, then clear the code and verify the repair with a test drive

What a low brake booster solenoid circuit really means

  • A low circuit code often results from a solenoid coil that has partially shorted or has high resistance from heat cycling, not from a completely dead solenoid, so resistance testing at operating temperature can reveal a fault that a cold test misses.
  • Corroded or loose ground connections at the chassis or engine block can cause a low voltage reading on the solenoid control circuit even when the solenoid itself is good, so always load-test grounds before condemning the solenoid.
  • The ABS module may set C0567 intermittently if system voltage drops during cranking or under heavy electrical load, so check for a weak battery or failing alternator before replacing parts.
  • A brake booster solenoid that tests good on the bench can still set this code if the ABS module's internal driver is failing, which is why checking the control signal from the module is a critical step.
  • This code does not always mean the brake booster itself is faulty; the solenoid is a separate component, and replacing the entire booster without testing the solenoid circuit is a common and expensive misdiagnosis.

Can I keep driving with C0567?

The vehicle remains drivable with C0567, but brake assist may be reduced, so you should avoid heavy braking or emergency stops and drive cautiously to a repair facility. Do not tow a trailer or drive in mountainous terrain until the fault is repaired, as increased brake pedal effort could compromise safety.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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