Powertrain, generic · Transmission

P0922 Gear Shift Forward Actuator Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Set when the drive circuit of the forward shift actuator of an automated manual gearbox shows a voltage that is too low for the current switching state. This usually points to a short to ground on a valve or motor line, or to an internal short in the actuator. Many controllers then switch the output off to protect the driver stage. No manufacturer documents this code publicly. A ZF patent drives each chamber of a double-acting shift cylinder through its own solenoid valve, and an Isuzu patent runs an electric shift motor in both directions, so a fault can affect one shift direction only. CARB requires circuit checks on outputs. P0923 is the opposite high fault, P0920 the open circuit, P0926 the reverse direction. Gears in this direction are blocked.

Likely causes

Drive wire chafed through and shorted to ground
Internal short in solenoid coil or shift motor
Water or corrosion bridging pins in the connector

Symptoms

  • Transmission warning light on
  • Certain gears can no longer be engaged
  • Gearbox may stay in neutral or hold one gear

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 forward actuatorwiring harnesstcm

Related codes

P0920P0921P0923P0926

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