Powertrain, generic (extended)

P28DA Clutch B Motor Position Sensor Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P28DA concerns the electrical circuit of the sensor that reports the rotor angle of the clutch B motor, and is chiefly stored when that signal disappears because a line is open. Electronic commutation of a brushless motor relies on this angle to energise U, V and W in the right order; it also lets the controller count revolutions and compare pump speed with the pressure sensor. Without a valid signal the clutch B pump is stopped and the gears on that shaft are no longer offered. Usual culprits are a broken sensor supply or ground, a pin pushed out of the connector, or a dead Hall or magnetic element inside the actuator. P28DB handles a signal that exists but is inconsistent; P28CB is the clutch A equivalent. Details are unpublished.

Likely causes

Open supply, ground or signal line of the clutch B motor position sensor
Pin pushed out or bent at the clutch B actuator connector
Failed sensing element inside the clutch B actuator

Symptoms

  • Clutch B out of service, half of the gears missing
  • Transmission warning lamp on
  • Motor speed codes for clutch B may be stored as follow-up faults

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,300
Time0.5–3.5 h

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

Parts involved

clutch motor position sensor bwiring harnesstcm

Related codes

P28DBP28D8P28D9P28CB

References: law.cornell.edu, cti-symposium.world.