OBD-II trouble code
P0920: Gear Shift Forward Actuator Circuit/Open
An open circuit on the forward shift actuator. The word 'forward' is the whole story: this transmission splits shift actuation by direction, so the signature is a car that reverses out of a space perfectly and then will not pull away.
Quick facts
- System
- Powertrain
- Category
- Transmission / Shift Control
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $140 – $3,000
- DIY difficulty
- Shop recommended
What does P0920 mean?
P0920 is stored when the transmission control module finds the circuit driving the gear shift forward actuator open — no current path, or a path so poor that no meaningful current flows when the actuator is commanded to move.
The first thing to take from this code is what the word forward is doing in the title. Some automated manual and dual-clutch designs do not use a single shift actuator that moves in both directions. They split shift actuation by direction, with one actuator responsible for engaging in the forward direction along the rail and another for the opposite direction. That architecture produces a symptom no other code in this block can produce: the forward gears become unavailable while reverse continues to work exactly as it always did. A car that backs out of a parking space normally and then refuses to pull away is not suffering from a bizarre partial gearbox failure — it is telling you which of two actuators has an open circuit, before a single measurement has been taken. Confirming that pattern is the first diagnostic step and it is free.
That split also hands the diagnosis something better than a specification sheet. The other direction's actuator is a working unit of very similar construction, mounted in the same housing, fed by the same architecture, and it can be commanded on demand. Rather than comparing the dead actuator against a published resistance range and hoping the published figure applies to this variant, command the working one and capture its current trace, then compare. A live reference from the same vehicle is stronger evidence than any number in a table, and it makes an ambiguous reading on the failed side much easier to interpret.
The consequence of an open, as opposed to any other electrical fault on this actuator, is that there is nothing left to work with. A weak actuator still produces force and the transmission can sometimes shift slowly around it. An open produces none, so the shift rail simply stays wherever it was. That is why P0920 tends to arrive as a car that cannot take up forward drive at all rather than as a car that shifts poorly, and it is also what makes this code deceptively dangerous: because reverse still works, drivers try to reverse out of situations they should not be in. A vehicle that can only travel backwards is not a vehicle that should be nursed home.
Common causes
- Open winding in the gear shift forward actuator motor
- Broken conductor in the actuator control circuit at a flex point
- Connector unseated, damaged or corroded at the actuator assembly
- Terminal pushed out of the connector body during previous work
- Worn motor brushes that have lost contact with the commutator
- Open supply leg or blown fuse feeding the actuator assembly
- Corroded crimp forming an effectively open joint under load
- Failed output driver inside the transmission control module
- Harness damage sustained during transmission or clutch removal
- Open in a shared ground where both direction actuators are affected
Symptoms
- Reverse working normally while forward gears are unavailable
- Vehicle unable to pull away with the engine running normally
- Transmission stuck in neutral when a forward gear is requested
- Warning lamp with a transmission fault message
- Gear indicator refusing to show a forward ratio
- No audible actuator movement when drive is selected
- Fault present from key-on rather than developing while driving
- Gear shift position control error code stored alongside
- Vehicle able to be reversed but not driven forward
- Fault appearing immediately after transmission harness work
Diagnostic steps
- 1.Confirm the directional pattern first: reverse working while forward gears are unavailable identifies which of the two actuators is at fault before any testing.
- 2.Scan for codes from the opposite-direction actuator, since both coded together points at shared supply, ground or connector rather than at one motor.
- 3.Command the working opposite-direction actuator and capture its current trace, then use it as a live reference for what a healthy unit on this vehicle looks like.
- 4.Command the forward actuator while watching current on both control leads; no current at all confirms the open rather than merely suggesting it.
- 5.Measure the forward actuator winding resistance at the connector with the harness disconnected and compare against both the specification and the reference trace.
- 6.Check supply and ground at the actuator connector with the key on, including any dedicated fuse feeding the assembly.
- 7.Perform a voltage drop test across each control lead under command, since a high-resistance joint can pass a static continuity check and still be open under load.
- 8.Inspect the connector body for pushed-out or spread terminals and confirm retention with a matching pin.
- 9.Flex the harness through its full range of drivetrain movement while monitoring, because an open at a flex point can close at rest.
- 10.If the harness and motor both measure good, back-probe the module output under command to identify a failed driver before condemning the assembly.
Repair cost
$140 – $3,000
Diagnosis is $150 to $400, and on this code it is well spent because the opposite-direction actuator provides a live comparison that shortens the job considerably. An open harness conductor or a repaired connector is $140 to $550 and is a common outcome where the fault followed recent transmission work. A gear shift forward actuator replaced as a serviceable external unit is $450 to $1,500 fitted with adaptation. Where the actuator is integrated into an internal shift assembly or a mechatronic unit requiring the transmission to come out, expect $1,700 to $3,000 including programming and adaptation. A failed output driver inside the transmission control module is $900 to $2,200 with coding. Recovery costs belong in the estimate — a vehicle that only moves in reverse is not one to drive to the workshop.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with gear shift forward actuator replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.