C0257 - Chassis Fault Code C0257 - Bromshydraulik & Trycksensorer
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System
Chassis (Brakes, Steering, Suspension)
Related Fault Codes
Technical Description
DTC C0257 designates an electrical or functional fault within the brake master cylinder pressure sensor circuit or internal pressure regulation valve circuit of the Electronic Brake Control Module (EBCM/HCU). The ECU monitors the 5V analog reference, signal return, and ground. The DTC triggers when the signal voltage is out of expected limits (< 0.2V or > 4.8V), exhibits a drift outside calibrated baseline offset (typically 0.5V at 0 bar), or detects an open/short circuit in the actuator/sensor loop.
Possible Causes
1. Glappkontakt, oxidation eller stiftvandring i kontaktdonet till ABS/ESP-hydraulaggregatet eller extern tryckgivare
2. Defekt integrerad eller extern bromstryckssensor (offset-drift eller internt elementfel)
3. Kabelskada (kortslutning till jord/spänning eller avbrott på 5V-referens/signalledning)
4. Intern defekt i EBCM-styrdonets ingångssteg eller drivkrets
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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