Code Definition

U1111 — CAN bus Circuit communication from body number 5 control module lost

System: Network Communication  |  Type: Manufacturer-Specific  |  Make: Toyota

About U1111

U1111 is a manufacturer-specific network communication diagnostic trouble code recorded for Toyota vehicles. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

When U1111 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

Scanning & clearing: Network (U) codes report communication faults between modules. When diagnosing U-codes, checking the vehicle's CAN bus integrity, supply/ground at each module, and reading all modules for related faults is usually the first step.

U1111 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

DTC U1111 is a Toyota specific network code set when a receiving ECU fails to receive the expected CAN data frames from the Body Number 5 control module within the allowed timeout period. The Body Number 5 ECU manages a defined group of body functions that vary by model and may include lighting, smart key, or seat related systems. When its periodic messages stop arriving, the receiving module concludes communication is lost and stores U1111, often disabling the features that depend on that module. Symptoms typically include warning lights and inoperative body features, and companion loss of co...

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