Code Definition

U0181 (00-2F) — Lost Communication with Headlamp Levelling Module

System: Network Communication  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About U0181

U0181 is a generic (obd-ii standard) network communication diagnostic trouble code. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

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.

Because U0181 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Body Control Module (BCM) and other networked control modules communicate with the headlamp levelling module over the Controller Area Network (CAN) bus to control and monitor automatic headlamp levelling operation. DTC U0181 is set when the BCM detects that expected CAN messages from the headlamp levelling module are not received within the calibrated timeout window, indicating a loss of communication with the module. This can occur due to a power supply, ground, CAN wiring, or module internal fault. When the code sets, automatic headlamp aiming becomes inoperative, the headlamps may defau...

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