U0471: Ungültige Daten vom Sensor A des Rückhaltesystems empfangen
Was zu tun ist
The airbag warning light means the airbags may not deploy correctly in a crash. The car drives normally, which is exactly why this gets postponed. It should not be.
This code names one of the crash sensors placed around the outside of the car — in the front bumper structure, the pillars, the doors or at the back. They are there because the airbag computer sits in the middle of the car and would learn about a crash too late on its own. These sensors give it the milliseconds it needs.
The single most useful thing you can tell a garage is whether that part of the car has ever been repaired. A front bumper, a radiator, a headlight, a wing, or any accident damage. These sensors get removed for that work, and they are very often refitted loosely, at the wrong angle, or replaced with a part from a slightly different model — any of which makes them read a real impact wrongly while testing perfectly at a standstill. Even a repair by a previous owner is worth mentioning.
Three things to insist on, exactly as at U0452. Do not accept having the light simply cleared. Do not accept a second-hand airbag module. And refuse absolutely if anyone offers to fit a resistor in place of a faulty sensor — it turns the light off and leaves a car whose airbags may behave unpredictably.
Was dieser Code bedeutet
A restraints system sensor is reporting a value that cannot be accepted as true. See U0400 for the family's framing and U0452 for the restraints system's own rules — including the ones about not working on it with the battery connected, and never fitting a resistor in place of a sensor. This page establishes the family that runs from here to U0479.
These are the remote crash sensors, and understanding why they exist explains almost everything about how they fail.
The restraints module sits in the middle of the vehicle, under the console or beneath the dash — the single most protected point in the structure and therefore the last place an impact is felt. That is deliberate; it has to survive to do its job. But it also means the module's own accelerometers learn about a collision comparatively late, and an airbag that has to be fully inflated before the occupant reaches it has only tens of milliseconds to work with.
So sensors are placed where the impact arrives first: on the front bumper beam or the front rails, in the B-pillars and sills, inside the doors, and at the rear for rear-impact protection. They exist to buy the module time, and their whole value is being at the extremities of the car — which is also the most exposed, wettest, most salted and most frequently repaired part of it.
Which gives the dominant cause by a wide margin: body repair. Front sensors bolt to structure that is removed for a bumper change, a radiator, a headlight or a front-end repair, and they are routinely disturbed, refitted loosely, refitted at the wrong angle, or replaced with a part from a different model year. Three points on that, each of which matters:
- Orientation is absolute. A sensor measures acceleration along a defined axis. Mounted backwards or rotated, it reads a genuine impact wrongly — and it will pass every static test.
- Mounting is part of the sensor. It reads the structure it is bolted to, so a loose bolt, a shim, paint or corrosion between it and the metal changes what it measures.
- Part numbers are not interchangeable. A sensor that fits and connects may be calibrated for a different structure entirely.
So the first question on any of these codes is what has been done to that end of the car, and it should be asked before a part is ordered.
One thing this family does not do is tell you where the sensor is. The letters are manufacturer-specific and are not standardised — A is not reliably the front left, or the front at all. Locating the sensor means the manufacturer's data, not an assumption, and guessing wrongly here means removing a bumper to find nothing.
Wahrscheinliche Ursachen
Hier anfangen
- Aufprallsensor bei der Karosseriereparatur verstellt · mittel
- Korrodierter oder loser Stecker · einfach
- Kabelbaum beschädigt · mittel
- Wasser in den Stecker eingedrungen · mittel
Seltener
- Mechanische Beschädigung durch Steinschlag · mittel
- Airbagsteuergerät defekt · Fachwerkstatt
Symptome
Beteiligte Bauteile
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