Chassis, generic

C0551 Longitudinal Acceleration Sensor Circuit/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0551 reports an electrical break in the longitudinal acceleration sensor circuit: the brake or stability module no longer gets a usable fore-aft signal, usually because the signal or supply wire is open or a plug has lost contact. Earlier layouts mounted a separate g-sensor close to the centre of gravity and cabled it to the ABS unit; a Kelsey-Hayes patent (now ZF) describes a capacitive element whose analog voltage rises with acceleration and moves it onto the ABS circuit board to drop wiring and connectors. No manufacturer explains C0551 in a public document. Without the input, four-wheel-drive ABS loses its wheel-independent speed reference and stability functions are normally switched off with ABS/ESC lamps lit, while base braking remains. C0553 and C0554 cover a low or high voltage, C0552 an implausible value.

Likely causes

Broken signal or supply wire between sensor and brake module
Corroded, loose or pushed-back terminal at the sensor plug
Internal open in the sensor or, on integrated designs, in the ABS/ESC unit

Symptoms

  • ABS and/or ESC warning lamp on
  • Stability, traction or hill-start assistance unavailable
  • ABS on four-wheel-drive vehicles regulates less precisely

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–2.5 h

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

Parts involved

longitudinal accel sensorsensor wiring

Related codes

C0552C0553C0554C0062

References: patents.google.com, mitsubishitechinfo.com.