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U0263 — Lost Communication Speech Recognition Module

Generic OBD-II · all makesNetwork / communication

U0263 indicates that the vehicle's network has lost communication with the speech‑recognition module, which is part of the infotainment system. The Powertrain Control Module (PCM) or other host controllers set this code when they no longer receive expected CAN messages from that module. As a result, voice‑command features may be unavailable and the check‑engine light will be illuminated.

Symptoms

What causes it — most likely first

1. Damaged or loose wiring/connector at the speech‑recognition module

Open circuits, broken insulation, or poor terminal contact on the CAN bus or power/ground leads will prevent the module from sending messages. This is the most common source of U0263.

2. Blown fuse or loss of power/ground to the module

If the fuse that supplies voltage to the speech‑recognition module is open, the module will be unpowered and invisible on the network, triggering the code.

3. Faulty speech‑recognition module itself

Internal electronic failure can render the module unable to transmit or respond, although this is less frequent than wiring issues.

4. Other modules or gateway device causing CAN bus disruption

A problem on the same CAN segment (e.g., a short, failed transceiver, or a module that pulls the bus low) can hide the speech‑recognition module’s messages from the rest of the network.

5. Software or calibration error preventing module initialization

If the module’s configuration is missing or the vehicle’s software hasn’t been updated, the module may not broadcast its presence, even though the hardware is functional.

6. Powertrain Control Module (PCM/ECM) fault (rare)

The PCM itself can fail to read any CAN messages, but this is an uncommon cause and should be investigated only after all other possibilities are eliminated.

How it's diagnosed

  1. Retrieve all stored diagnostic trouble codes (DTCs) and note any other U‑codes or P‑codes that may indicate a broader network problem.
  2. Visually inspect the wiring harness and connectors leading to the speech‑recognition module for damage, corrosion, or looseness.
  3. Check the fuse that powers the module; replace any blown fuse and verify that the module receives proper voltage and ground.
  4. Use a digital multimeter or oscilloscope to verify CAN‑High (≈2.5‑3.5 V) and CAN‑Low (≈1.5‑2.5 V) signals at the module’s connector while the vehicle is in the appropriate ignition state.
  5. If bus voltages are correct, perform a network scan with a compatible diagnostic tool to confirm whether the module responds when powered.
  6. If the module remains silent, substitute a known‑good unit (if available) or reload the module’s software/calibration before considering PCM replacement.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make
Related codesU0260 — Lost Communication Seat Control SwitchU0261 — Lost Communication Seat Control SwitchU0262 — Lost Communication Audio Amplifier BU0264 — Lost Communication Camera Module ReaU0265 — Lost Communication Image Processing SeU0266 — Lost Communication Image Processing Se

Frequently asked

Is it true that I should replace the PCM when I see U0263?

No. The PCM is rarely at fault for this code. Most of the time the problem lies in wiring, a blown fuse, or a failed speech‑recognition module itself. Replace the PCM only after all other potential causes have been ruled out.

Can a blown fuse trigger U0263?

Yes. If the fuse that supplies power to the speech‑recognition module opens, the module will be unpowered and will not communicate, causing the code to set.

Could aftermarket accessories cause this fault?

Yes. Non‑OEM devices that tap into the CAN bus or add electrical loads can interfere with network communication and make the speech‑recognition module appear offline.

What does the speech‑recognition module do, and will I notice any other symptoms besides a CEL?

The module processes voice commands for functions such as phone, navigation, and media. When it fails, you may lose voice activation, see a warning message on the infotainment display, or experience missing navigation voice prompts.