What it means
Communication with the Moveable Roof Control Module was not received as expected.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
The Moveable Roof Control Module reports roof status and receives control information through the vehicle network. U020A indicates that a monitoring module did not receive valid expected messages from this module for its calibrated period.
Common causes
Most likely first.
- Module unpowered
- Gateway module routing CAN messages incorrectly
- 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
- Capture freeze-frame information and scan all modules for communication faults to determine whether the roof module alone is missing.
- Use a capable scan tool to attempt communication with the Moveable Roof Control Module and check which other modules report it offline.
- Find the module and network connections using vehicle-specific wiring information, then inspect connectors, harnesses, and grounds for moisture, corrosion, looseness, or damage.
- Test the module’s power and ground circuits under the manufacturer’s specified conditions.
- If supply circuits pass, test the applicable CAN wiring and termination to specification and examine gateway routing if other network faults are present.
Common fixes
- Repair a loose, corroded, wet, or damaged roof-module connector or wiring.
- Restore a faulty module power feed or ground.
- Repair a CAN bus or termination issue identified by testing.
- Correct a gateway routing fault if communication evidence points to it.
Can I keep driving?
The movable roof may not operate or report its position; keep it secured and do not attempt roof movement while driving. If it is stuck in a position that leaves panels unsecured or visibility impaired, do not continue until the vehicle is safe.
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.