U0480 High Generic / SAE

U0480: Invalid Data Received From Seat Belt Pretensioner Module B

Network and Communication Invalid Data Received

What to do

Your seat belts may not tighten properly in a crash, and that matters more than most people realise: the belt does most of the work, and the airbag only assists it.

In the first fraction of a second of an impact, a small charge in the belt buckle or reel yanks the slack out of the belt so you start slowing down with the car rather than a moment later. This code means the car cannot trust what that system is telling it.

There is one thing worth checking yourself, and it fixes a surprising number of these. Look inside the belt buckle. It faces upwards and collects coins, crumbs, grit and spilt drink. A buckle dirty enough to read as "fastened" when nothing is clipped in is a real and common fault — and if the car thinks you are belted when you are not, it will also choose the wrong airbag setting for you in a crash. Carefully clean it out; do not spray lubricant into it.

Two rules that must not be bent. A pretensioner that has already fired is replaced, never reset — they work once. And any seat belt worn in a crash should be replaced even if it looks perfect, because the webbing has already stretched to do its job.

As everywhere on this system: do not have the light cleared, and never accept a resistor fitted in place of a component.

What this code means

A seat belt pretensioner module is broadcasting data that cannot be accepted as true. See U0452 for the restraints system's framing and safety rules.

One numbering note first, because the letter looks like an error otherwise. The standard's pretensioner module A sits in the letter-suffixed part of the U047x range rather than at a decimal number, so the first of these codes readable here is B. A scan tool reporting pretensioner module A is not reporting something this page covers.

Now the part that changes how the whole restraints system should be understood. The seat belt does most of the work in a crash, and the airbag is supplementary to it — which is exactly what the letters SRS on the trim panels stand for. A pretensioner is what makes the belt good enough to be the primary restraint.

In the first milliseconds of an impact — before the airbag has begun to inflate — a pyrotechnic charge in the buckle or the retractor pulls several centimetres of slack out of the belt, tightening it against the occupant so that they begin to decelerate with the car rather than after it. Then a load limiter lets the webbing pay out again at a controlled force, so that the belt restrains without concentrating the whole load on the chest. Some vehicles add a reversible motorised pretensioner that tightens during emergency braking and releases if no impact follows.

What this module publishes, and why invalid data matters, has a second consequence that is easy to miss. It reports pretensioner readiness — and buckle state. Modern vehicles change the airbag's deployment strategy according to whether the occupant is belted, deploying earlier and firmer for someone who is not. So a wrong buckle report does not merely silence a reminder chime; it can select the wrong deployment for the person in the seat.

Two ordinary causes account for most of these, and the first is almost comic until it is understood.

Debris in the buckle. Coins, crumbs, grit and drink residue collect in a slot that faces upwards. A buckle contaminated enough to read as fastened when it is not removes the reminder entirely and misreports occupant state — and it is cleaned rather than replaced.
The wiring under the seat, which is disturbed by every seat slide, every object pushed underneath, and every job done in the footwell.

And one rule that must not be bent. A pretensioner is a single-use pyrotechnic device. One that has fired is replaced, never reset — and any belt that was worn in a collision should be replaced even if it looks perfect, because the webbing stretches and the load limiter has already done its work.

Likely causes

Start here

Damaged wiring under the front seats · moderate
Corroded or loose connector · easy
Restraints system locked after a previous deployment · specialist

Less common

Impact sensor disturbed during body repair · moderate
Faulty restraints control module · specialist
Damaged data bus wiring · 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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