Chassis, generic

C0269 Brake Vacuum Sensor

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

C0269 lacks a J2012 entry in the sources available, and a vacuum sensor meaning appears nowhere. On GM vehicles, where PIP5094 names the code, AA1Car translates it as Excessive Dump/Isolation Time: the brake module has held wheel pressure isolated or released for longer than its software allows. In GM-type ABS the isolation valve closes to stop pressure rise and the dump valve opens to let fluid into a low-pressure accumulator. A Lucas patent explains why dump time is limited: at very low speed a recovering wheel still looks locked, so dumping is cut off once it exceeds a weighted average of earlier cycles. Typical causes are a faulty wheel speed signal, a sticking valve or a weak return pump.

Likely causes

Erratic or weak wheel speed signal making a wheel appear locked
Sticking isolation or dump valve in the hydraulic unit
Weak return pump or full low-pressure accumulator

Symptoms

  • ABS warning lamp on, ABS disabled
  • Long or soft brake pedal feel during an ABS stop

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–1,500
Time0.5–3.5 h

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

Parts involved

abs hydraulic unitwheel speed sensorabs control module

Related codes

C0268C0110C0035C0258

References: static.nhtsa.gov, aa1car.com, patents.google.com, patents.google.com.