What it means
A control module received invalid data from the park lock/pawl control module. The code identifies a data validity fault; the specific affected function depends on the vehicle.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
The park lock or pawl control module reports the status of the mechanism that secures the transmission in Park. U04BD is set when a receiving module judges that report invalid, which can prevent the vehicle from reliably confirming or selecting Park.
Common causes
Most likely first.
- Fault in the transmitting module
- Network wiring or connector fault
- Module power or ground fault
- Software or configuration mismatch
Symptoms
- A transmission or park-system warning may appear
- Selecting or confirming Park may be affected
How to diagnose it
- Record freeze-frame data and scan transmission and body modules for related park lock, pawl, or communication codes.
- Check live data for park lock or pawl status while selecting Park, and note whether the reported state agrees with the selector and vehicle behavior.
- Inspect the park lock/pawl module connector and network harness for damage, corrosion, loose pins, or water intrusion.
- Check the module's power and ground against the manufacturer's specification.
- Test the network wiring and connector terminals for opens, shorts, or poor connections using the vehicle wiring information.
- If the network and supplies pass, check software or configuration compatibility before diagnosing the module itself.
Common fixes
- Reconnect or repair a loose or corroded park lock/pawl module connector.
- Repair damaged network wiring or connector terminals.
- Restore the module's faulty power or ground connection.
- Correct an applicable software or configuration issue.
- Replace the park lock/pawl control module only after testing confirms it is transmitting invalid data.
Can I keep driving?
Do not rely on Park to hold the vehicle if the park status is uncertain; secure it with the parking brake and avoid driving if gear selection is unreliable. A vehicle that cannot confirm Park may roll or become difficult to secure.
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.