P0923 OBD-II Trouble Code: Gear Shift Forward Actuator Circuit High

P0923 code definition

The P0923 trouble code notes a problem with the gear shift forward actuator circuit

What the P0923 code means

The P0923 code is a generic OBD-II trouble code that detects an issue with the transmission’s gear shift forward actuator circuit. The forward actuator is in charge of shifting the transmission into a forward-moving gear (as opposed to reverse). If the powertrain control module (PCM), or the engine control module (ECM) notices that the voltage reading from the gear shift forward actuator circuit is unusual, the P0923 code will be triggered.

What causes the P0923 code?

There are a few different problems that can result in the P0923 trouble code being detected:

• Malfunctioning gear shift forward actuator
• Damaged or defective forward gear guide rail
• Damaged or defective shift shaft
• Mechanical problem in the internal transmission
• In very rare cases, a malfunctioning PCM, ECM, or transmission control module
• Faulty electrical components in the transmission system, such as shorted wires or open connectors

What are the symptoms of the P0923 code?

When the P0923 trouble code is detected, the Check Engine Light will likely illuminate on the vehicle’s instrument panel. The car may also experience problems shifting into gear, and may be entirely unable to access a forward-moving gear. If the car is drivable, it is likely that the fuel efficiency will be reduced.

How does a mechanic diagnose the P0923 code?

The P0923 code will be diagnosed using a standard OBD-II trouble code scanner. A trained technician will use the scanner’s freeze frame data to gather information about the code, and to look for any additional trouble codes that are present. If multiple codes are detected, the mechanic should take care of them in the order in which they appear on the scanner. Next, the trouble codes will be reset, and the vehicle will be restarted, so the mechanic can see if the code remains detected. If it does not, then there likely was an erroneous trigger, or the code represented an intermittent error.

If the trouble code returns, then the mechanic will start with a visual inspection of the transmission system’s electrical components. All wires, connectors, fuses, and circuits should be checked, and replaced if they are in any way damaged. The technician can then inspect the gear shift forward actuator, the forward gear guide rail, and the shift shaft.

If the P0923 code is still detected, a more comprehensive inspection of the transmission and PCM will be in order.

It is important that the mechanic stop after any component is replaced to reset the trouble codes and restart the vehicle. This will allow the mechanic to know when the problem has been fixed.

Common mistakes when diagnosing the P0923 code

The most commonly made mistake when diagnosing the P0923 code comes from a failure to follow the basic OBD-II diagnosis protocol. This protocol should be followed at all times, step by step, to ensure that inspections and repairs are as quick, thorough, and effective as possible. If the protocol is not followed, it is possible that a complex component will be erroneously replaced, when a simpler fix was all that was needed.

How serious is the P0923 code?

The P0923 trouble code may or may not keep a car from being drivable. Even if the car is drivable, to drive it under this condition will run the risk of causing further damage to the transmission. For this reason, the P0923 code should be addressed as soon as it is detected.

What repairs can fix the P0923 code?

Possible repairs for the P0923 code include:

• Replacement of the gear shift forward actuator
• Replacement of wires, connectors, and circuits in the system
• Replacement or adjustment of the forward gear guide rail
• Replacement or adjustment of the shift shaft
• In very rare cases, replacement of the PCM, ECM, or transmission control module

Additional comments for consideration regarding the P0923 code

It is unlikely that the P0923 trouble code signals a defective PCM, ECM, or transmission control module, so all other potential issues should be checked before one of these is assumed to be the error. However, if a control module does need to be replaced, it will also need to be reprogrammed.

Need help with a P0923 code?

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