Chassis, generic

C0291 Brake Pedal Apply Sensor Circuit Malfunction

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0291 is in no publicly available J2012 table, and no maker uses it for a brake apply sensor. GM names the number in its PIP5094 keyword list, and AA1Car's table of GM brake codes reads it as Lost Communications With BCM, a lost data link to the body module. An apply sensor tells the control units whether, and how firmly, the pedal is pressed. GM handles that job with a pedal position sensor: on the 2011 Saab 9-4X it is read by the body module, which needs 9 to 16 V supply and stores separate subcodes for grounded or open lines, battery shorts, implausible jumps and a missing rest position learn. A failure there affects stop lamps, shift lock and the electric park brake release.

Likely causes

Chafed wire or loose connector at the pedal sensor
Pedal sensor replaced or pedal adjusted without relearning the rest position
Data link to the body module interrupted (GM meaning of the number)

Symptoms

  • Stop lamps stay on or do not light
  • Cruise control or shift lock release not working
  • ABS or stability control warning lamp on

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–300
Time0.3–1.5 h

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

Parts involved

brake pedal position sensorbrake control modulesensor wiring

Related codes

C0290C0277

References: static.nhtsa.gov, aa1car.com, saabwisonline.com.