U01BA: Lost Communication With Park Lock/Pawl Control Module

What it means

Communication with the Park Lock/Pawl Control Module was not received as expected. The code does not specify the vehicle's parking-lock design.

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/Pawl Control Module manages or reports the mechanism that helps secure the vehicle in Park. This code sets when other modules stop receiving its expected network messages, so the parking-lock design and the cause of the communication loss are not identified by the code alone.

Common causes

Most likely first.

1. Module unpowered
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Record freeze-frame data and all module codes, and note any warnings about Park or other communication faults.
2. With a compatible scan tool, check whether the Park Lock/Pawl Control Module responds and whether related status messages are missing.
3. Inspect the module’s power, ground, connectors, and wiring for damage, corrosion, looseness, or water entry.
4. Check the network wiring and connectors on the module’s communication branch for opens, shorts, or poor contact.
5. If power and wiring are sound, have gateway routing and CAN termination tested to the manufacturer’s specification before condemning the module.

Common fixes

• Restore a loose, corroded, or damaged power or ground connection at the module.
• Repair damaged network wiring or connector terminals on the Park Lock/Pawl Control Module branch.
• Correct a gateway routing fault if diagnostic testing confirms it.
• Repair or replace a CAN terminating resistor if it is outside the manufacturer’s specification.

Can I keep driving?

Do not rely on the vehicle to secure itself in Park while this fault is active; use the parking brake and follow the owner’s manual, and avoid driving if the vehicle will not reliably select or hold Park. Arrange prompt diagnosis because a failed or unconfirmed parking lock can let the vehicle roll.