OBD-II trouble code
P0924: Gear Shift Reverse Actuator Circuit/Open
An open circuit on the reverse shift actuator — the exact inverse of the forward code. The car drives away perfectly and then cannot be parked, which is a fault you are far more likely to discover in a supermarket car park than on the road.
Quick facts
- System
- Powertrain
- Category
- Transmission / Shift Control
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $140 – $3,000
- DIY difficulty
- Shop recommended
What does P0924 mean?
P0924 is stored when the transmission control module finds the circuit that drives the gear shift reverse actuator open, with no usable current path when the actuator is commanded. On an automated manual or dual-clutch transmission that splits shift actuation by direction, this is the half of the mechanism responsible for engaging reverse.
The signature is the mirror image of the forward-side open, and it changes almost everything about how the fault reaches you. Forward drive is unaffected, so the car pulls away, changes gear and cruises exactly as it always has. The failure only exists in a situation the driver encounters a handful of times a day and never at speed. That has two consequences worth stating plainly. The first is that the fault is often discovered long after it happened — the driver reverses off a driveway in the morning, drives all day, and finds the problem at a parking space that evening, with no idea which of the day's events is relevant. The second is that this is not an emergency in the way the forward-side codes are. A car that cannot reverse is entirely capable of getting itself to a workshop. It is simply a car that must be parked somewhere it can be driven out of forwards, which is a real constraint and an easy one to plan around.
The way a reverse actuator circuit fails also tends to differ from the forward one, because the two live completely different lives. The forward side works for hours at a time and suffers accordingly from heat. The reverse side is commanded for a few seconds per journey and then sits idle, and idle is its own kind of stress. Contacts that are never wiped by current accumulate oxide, moisture sits undisturbed in a connector that is never warmed by use, and grease in the mechanism dries where it was last left. So where the forward-side faults skew toward thermal fatigue, an open on the reverse side skews toward corrosion, a terminal that has slowly lost tension, and damage that has been present for a while without anyone noticing.
There is one more route by which this code arrives, and it disguises itself well. Reversing cameras, park distance sensors, automatic tailgates and hill-hold strategies commonly key off a confirmed reverse engagement rather than a switch on the shifter. When the module cannot confirm reverse, those features go quiet too, so the complaint that lands at the counter can be "my parking sensors stopped working" rather than anything about the transmission. Chasing the camera on a car storing P0924 is time spent on a symptom.
Common causes
- Open winding in the gear shift reverse actuator motor
- Corrosion in a connector that is rarely warmed by use
- Terminal that has lost spring tension and no longer makes contact
- Broken conductor in the reverse actuator control circuit
- Connector unseated or damaged during earlier work in the area
- Open supply leg or blown fuse feeding the reverse actuator
- Worn motor brushes that have lost contact with the commutator
- Failed output driver inside the transmission control module
- Harness damage sustained during clutch or transmission removal
- Moisture ingress into a connector left undisturbed for long periods
Symptoms
- No reverse gear while all forward gears work normally
- Vehicle refusing to select reverse with no unusual noise or feel
- Warning lamp with a transmission fault message
- Reversing camera or park distance sensors failing to activate
- Automatic tailgate or mirror dip on reverse no longer operating
- Fault noticed hours after the last successful reverse engagement
- Gear indicator refusing to display R when reverse is selected
- No audible actuator movement when reverse is requested
- Hill-hold or park assist behaving unexpectedly
- Fault present from key-on with no preceding driving symptom
Diagnostic steps
- 1.Confirm the directional pattern: all forward gears working with reverse unavailable identifies the reverse actuator before any measurement is taken.
- 2.Ask when reverse last worked, since the fault may have been present for days without the driver connecting it to anything.
- 3.Check whether reverse-linked features such as the camera and park sensors have also stopped, which confirms the module is not seeing confirmed reverse engagement.
- 4.Command the reverse actuator with a scan tool while monitoring current on both control leads; no current at all confirms the open.
- 5.Measure the actuator winding resistance at the connector with the harness disconnected.
- 6.Inspect the connector face carefully for oxide, green corrosion and loss of terminal tension, which is the characteristic failure on a rarely-used circuit.
- 7.Test terminal retention with a matching pin rather than assuming a connector that looks seated is making contact.
- 8.Check supply and ground at the actuator connector with the key on, including any dedicated fuse.
- 9.Perform a voltage drop test under command, because a corroded joint can pass a static continuity check and still be open under load.
- 10.If the harness and motor both measure good, back-probe the module output under command before condemning the actuator assembly.
Repair cost
$140 – $3,000
Diagnosis is $150 to $400. Because the vehicle is drivable, this is one of the few codes in this family where you can book the work rather than pay for recovery, and that saving is real. A corroded connector cleaned and resealed, or a harness conductor repaired, runs $140 to $600 and is a more likely outcome here than on the forward side, given how these circuits fail. A reverse actuator replaced as an external serviceable unit is $450 to $1,500 fitted with adaptation. Where it sits inside the transmission or within a mechatronic unit, $1,700 to $3,000 including programming. A failed module driver is $900 to $2,200 with coding.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with gear shift reverse 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.