U0481 Moderate Generic / SAE

U0481: Invalid Data Received From Automatic Lighting Control Module

Network and Communication Invalid Data Received

What to do

Do not leave the light switch on AUTO while this is stored. Turn the lights on yourself.

And there is something worth knowing here even after it is fixed, because it catches people in perfectly healthy cars. Your daytime running lights are at the front only. In fog, heavy rain or fading light, you see a well-lit road ahead and a fully lit dashboard — while showing nothing at all at the back. Being invisible from behind in exactly those conditions is one of the commonest hazards on the road today.

So: switch the headlights on properly, and check the rear lights are actually lit. Look at the reflection in a shop window or a wall behind you, or ask somebody. A lit dashboard proves nothing — on most cars it is lit either way.

One thing to check yourself before paying anyone. The light sensor is a small dome on the glass, usually at the bottom of the windscreen or up by the mirror. Is anything covering it? A dashcam, a phone holder, a sat-nav mount, a tinted strip across the top of the screen. And if the windscreen has been replaced recently, say so — the sensor has to be transferred and bonded to the new glass correctly, and it often is not.

What this code means

The automatic lighting module is broadcasting data that cannot be accepted as true. See U0400 for the family's framing.

This module decides when the vehicle's lights come on — from an ambient light sensor, usually a small dome at the base of the windscreen or in the mirror mount, combined with the rain sensor and road speed.

And it sits on top of a genuine, well-documented road safety problem that has nothing to do with anything being broken, which is why this page is longer than the function deserves.

Daytime running lights are at the front only. They are bright, they light the road surface ahead in dusk and rain, and the instrument panel is illuminated permanently on nearly every modern car. So a driver in fog, heavy rain or falling light sees a lit road ahead and a lit dashboard, and has no cue at all that the vehicle is showing nothing at the back. Being effectively invisible from behind in exactly the conditions where it matters most is now one of the commonest hazards on the road, and it happens on healthy vehicles.

A fault in the automatic system makes it likelier rather than causing it. The module may leave the lights off when they should be on, cycle them, or report a light level the rest of the vehicle rejects.

So the instruction here is simple and worth following even after the fault is fixed: switch the lights on manually rather than leaving the switch on AUTO, and confirm the rear lights are actually lit — by their reflection in a window or wall behind the car, or by asking somebody. A lit dashboard does not tell you the tail lights are on; on most vehicles the panel is lit either way.

Where the fault usually is has an answer specific to this module: the sensor is on the glass. So it is defeated by things that have nothing to do with electronics — a dashcam or phone mount over it, a tint strip or sun band across the top of the screen, a windscreen replaced without the sensor being transferred properly, or the optical gel pad behind the sensor lifting away from the glass. Any of those makes the module report a light level that cannot be reconciled with the time of day.

Likely causes

Start here

Disconnected sensor connector · easy
Corroded or loose connector · easy
Faulty receiving module input · specialist

Less common

Module not coded to the vehicle · specialist
Damaged data bus wiring · moderate
Damaged wiring harness · moderate

Symptoms

Components involved

Information, not instruction

CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.

Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

Community experience

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