What it means
The vehicle bus reports loss of communication with the seat control switch module C. Buttons for seat adjustment, lumbar and memory recall on this position stop responding.
How it works
Seat control switch module C reads the controls for its assigned seat functions and communicates requests to the seat system over the vehicle network. U0271 is stored when another module cannot receive a response from module C, which can disable adjustment, lumbar, or memory controls on that seat position.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
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
- Scan the body and seat modules for codes and identify which module logged U0271, checking whether other communication faults point to a wider network issue.
- Use the scan tool to check whether seat control switch module C is present and whether its communication loss is current or recorded from an earlier event.
- Operate the controls for the seat position served by module C and inspect its switch panel, connector, and harness for damage, spills, looseness, or corrosion.
- Check module C's power and ground circuits to the manufacturer's specification, since a supply fault can prevent the switch module from communicating.
- Test its network wiring for opens, shorts, or poor terminal contact, and consider module C failure only after its power, ground, and bus circuits pass.
Common fixes
- Reconnect or clean and secure the module C connector or seat switch connection.
- Repair damaged wiring or poor terminals in module C's power, ground, or network circuits.
- Restore the failed power or ground feed to seat control switch module C.
- Replace module C if its circuits are intact and it remains unreachable on the network.
Can I keep driving?
The communication fault generally does not affect driving, but confirm the seat is securely positioned and you can reach the pedals and controls before setting off. Avoid driving if the seat cannot be locked in a safe position.
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.