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C0091 Chassis

Hydraulic Brake Pressure Sensor Circuit Range/Performance

The brake pressure sensor signal is outside the plausibility band relative to pedal application. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

Affected components

  • Brake pressure sensor
  • Abs control module

Common causes

  • High likelihood: Sensor drift with age
  • Low likelihood: Internal hydraulic block leak
  • Low likelihood: Sensor element aged beyond calibration window

Possible symptoms

  • ABS warning light on
  • ESC/stability control deactivated
  • Possible reduced brake assist
  • Speedometer may behave erratically

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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