C0269Brake Vacuum Sensor
- Generic OBD-II code · Chassis
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- ABS warning lamp on, ABS disabled
- Long or soft brake pedal feel during an ABS stop
- Likely causes
- LikelyErratic or weak wheel speed signal making a wheel appear locked
- PossibleSticking isolation or dump valve in the hydraulic unit
- PossibleWeak return pump or full low-pressure accumulator
- Repair
- Hard · Usually a job for a workshop.Typical cost: €50 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.