Chassis, generic

C05C8 Brake Pressure Sensor F Circuit/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

General circuit fault of pressure sensor F, most often a break in one of its three wires (supply, signal, ground) or a connector that has lost contact. Where the reading ends up depends on the input circuit: Honeywell notes that after a power or ground loss the output goes high with a pull-up and low with a pull-down resistor, so an open line can look like C05C6 or C05C7 unless the module tells them apart. Saab/GM flags an open or high resistance on the brake pressure signal or 5 V reference after 0.1 s. Bosch advises checking the live value of a modulator-mounted pressure sensor before buying an expensive part. No manufacturer publishes C05C8 for sensor F. Repair wiring or connector, then clear and retest.

Likely causes

Connector unplugged, corroded or with pushed-back pins
Broken wire in the sensor harness
Internal open circuit in sensor F

Symptoms

  • ABS and ESC warning lamps on
  • Stability control and brake assist functions not available

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–1,200
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake pressure sensor fsensor wiring

Related codes

C05C6C05C7C05C9C05A1

References: saabwisonline.com, prod-edam.honeywell.com, techtips.ie.