Chassis, generic

C0609 Park Brake Switch Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The park brake switch is the driver's apply and release button for an electric parking brake; on some cars it also reports lever or button state to other modules. C0609 covers an electrical fault in its circuit, such as an open contact, a short to ground or supply, or an unplugged connector. Continental's patent for a redundant EPB button gives each switch level its own supply and ground and measures resistor potentials to find these faults, then still reads the driver's request from the intact channel. Audi logs C060900, under the same switch title, in J623, the engine control unit of 2022–2024 Q4 e-tron models, with a drive system warning and sometimes no gear engagement; TSB 2074088 calls for a 15-minute terminal 30 reset and earth strap work.

Likely causes

Connector at the switch or in the dash not fully engaged
Poor ground or control unit software (Audi Q4 e-tron case)
Worn, contaminated or corroded switch contacts, e.g. after spilled drinks

Symptoms

  • Park brake or drive system warning in the cluster
  • Parking brake does not respond to the button
  • Gear selection refused in some electric models

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–350
Time0.3–1.5 h

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

Parts involved

park brake switchepb control module

Related codes

C060AP05E3U0128

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