Powertrain, generic · Transmission

P0924 Gear Shift Reverse Actuator Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Concerns the drive circuit that moves the shift mechanism of an automated manual gearbox in the reverse shift direction, i.e. opposite to the forward actuator. It does not mean the reverse gear itself. Depending on design this is the second solenoid valve of a double-acting shift cylinder or the second rotation direction of an electric shift motor. The code sets when the module finds this output open or electrically faulty. No manufacturer documents the code publicly. A ZF patent assigns one 3/2 solenoid valve to each cylinder chamber, an Isuzu patent reverses the shift motor depending on shift direction. CARB requires circuit checks on outputs. P0925 to P0927 are the siblings, P0920 the forward direction. Gears in this direction cannot be engaged.

Likely causes

Loose, corroded or unplugged connector at the shift actuator or valve
Broken drive wire between module and actuator
Open solenoid coil or motor winding in the actuator
Faulty driver stage in the transmission control module

Symptoms

  • Transmission warning light on
  • Some gears cannot be selected or the gearbox stays in neutral
  • Gear changes out of the current gear may fail

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,000
Time0.5–5 h

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

Parts involved

gear shift reverse actuatorwiring harnesstcm

Related codes

P0925P0926P0927P0920P0910

References: law.cornell.edu, patents.google.com, patents.google.com.