What it means
The gear shift control module A reports a performance fault. Shift command exchange is impaired.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Gear Shift Control Module A handles shift-related requests and exchanges data with other vehicle controllers. This code sets when Module A is present but its operation or reported shift-command performance does not meet the expected criteria.
Common causes
Most likely first.
- Internal module fault
- Firmware corruption
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Scan all modules and save freeze-frame data and related transmission codes to see when Module A's performance fault occurred.
- Use a scan tool to check whether Module A is online and whether its status or shift-command data is missing, implausible, or delayed.
- Inspect Module A's connectors, power and ground connections, and wiring for looseness, corrosion, damage, or moisture.
- Check the vehicle battery and charging system, since unstable supply voltage can disrupt module operation.
- If power, ground, and connections are sound, have Module A and its software checked using the vehicle manufacturer's diagnostic procedure.
Common fixes
- Clean and secure Module A connectors and repair damaged wiring.
- Repair a poor power or ground connection to Module A.
- Restore or update Module A firmware if the manufacturer identifies a software issue.
- Replace Module A if testing confirms an internal fault.
Can I keep driving?
If shifts are harsh, delayed, slipping, or the vehicle is in limp mode, avoid hard acceleration and long trips; arrange prompt diagnosis because unreliable shifting can worsen or leave you without the expected gear. Stop somewhere safe if the transmission loses drive or the vehicle becomes difficult to control.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.