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U0271 — Lost Communication Seat Control Switch Module C

Generic OBD-II · all makesNetwork / communication

The U0271 code indicates that a communication error has occurred between the vehicle's network and the Seat Control Switch Module C. This module is responsible for seat adjustment functions, and when communication is lost, the seat may become inoperative or behave erratically. The code is set when the module fails to respond to periodic messages from other control units on the CAN bus.

Symptoms

What causes it — most likely first

1. Faulty Seat Control Switch Module C

Internal failure of the module due to water intrusion, corrosion, or electrical damage is the most common cause. The module may not power up or communicate on the network.

2. Open or shorted power or ground circuit to the module

A blown fuse, broken wire, or poor ground connection can prevent the module from operating, leading to a loss of communication.

3. Damaged or corroded wiring/connectors in the CAN bus

Faulty wiring between the module and the rest of the vehicle network can interrupt data transmission. Look for chafed, pinched, or corroded wires and terminals.

4. Faulty CAN bus termination or network issue

A problem with the terminating resistors or another module on the same bus can disrupt communication for multiple modules, including the seat control switch module C.

5. Other control module interfering with communication

A malfunctioning module on the same network branch may flood the bus with errors, preventing the seat module from responding. This is less common but possible.

6. PCM/ECM fault (rarely the cause)

The powertrain control module is almost never responsible for this code. It should only be suspected after all other possibilities are exhausted and if there is evidence of internal network failure.

How it's diagnosed

  1. Use a scan tool to check for other communication codes (U-codes) to determine if the issue is isolated to the seat module or affects multiple modules.
  2. Inspect the seat control switch module C and its connectors for signs of water damage, corrosion, or loose connections. Check related fuses.
  3. Verify battery voltage and ground at the module's power and ground pins using a digital multimeter.
  4. Test the CAN bus wiring between the module and the network for continuity, shorts to power/ground, or open circuits. Check terminating resistor values if accessible.
  5. Attempt to communicate with the module using a scan tool. If no response, and power/ground/wiring are good, replace the seat control switch module C.
  6. If the module communicates but the code returns, check for intermittent wiring issues or a faulty module on the same network branch causing interference.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make
Related codesU0269 — Lost Communication Image Processing SeU0270 — Lost Communication Image Processing SeU0272 — Lost Communication Seat Control SwitchU0273 — Lost Communication Lighting Driver ConU0274 — Lost Communication Lighting Driver ConU0275 — Lost Communication Lighting Driver Con

Frequently asked

What does the U0271 code mean?

It means the vehicle's communication network has lost contact with the Seat Control Switch Module C, which controls seat adjustments. The module is not responding to data requests.

Can I still drive with this code?

Yes, the vehicle will likely drive normally, but seat adjustment functions may be inoperative. If the seat is stuck in an unsafe position, address it before driving.

Is the PCM/ECM the cause of this code?

Almost never. The U0271 code is typically caused by a fault in the seat module itself, its power supply, or wiring. Replacing the PCM is not the correct repair and will not fix the problem.

How is this code diagnosed?

A technician will check for other communication codes, inspect the seat module and wiring, verify power and ground, and test the CAN bus signals. The module is often the culprit if all else is good.