OBD-II code family
Invalid Data Received From Restraints System Sensor (U0471–U0478)
8 codes describing the same fault on 8 enumerated slots. The letter is the index your manufacturer assigned — it is not a physical difference, and it does not carry across makes.
What these codes mean
This family is the close cousin of the Lost Communication restraint sensor codes, and the difference between them matters more than the shared subject suggests. A Lost Communication code means the airbag module heard nothing at all. An Invalid Data code means it heard the sensor perfectly well and did not believe what it said.
That distinction redirects the whole diagnosis. Silence points at wiring, connectors and power — the physical path. Implausible data points at the sensor itself, at its calibration or configuration, or at a genuine disagreement between sensors that the module is right to distrust. A sensor reporting a large impact while every other sensor on the vehicle reports nothing will be rejected, and correctly so.
The letter — A through H in this family — is the manufacturer's slot index for that sensor and carries no generic meaning. There is no industry table mapping letters to physical positions; the restraint wiring diagram for your specific vehicle is the only authority. As with the Lost Communication family, a high letter implies a vehicle with many restraint sensors, which means a large or well-equipped one.
The most common real causes are a sensor that has been disturbed or replaced without being configured to the vehicle, a sensor mounted loose or on a bracket deformed by earlier damage, water intrusion producing plausible-looking but wrong readings, and modules that were replaced with units carrying incompatible software. Prior collision repair is a recurring theme — a sensor bolted back to a bent bracket reads a world that is tilted relative to the one every other sensor sees.
Supplemental restraint work carries real risk. Disable the system and observe the manufacturer's specified wait time before disconnecting anything, because these circuits fire pyrotechnic devices. And treat the code as urgent: a module that distrusts one of its inputs will usually disable part of the restraint system rather than risk acting on bad data.
Which restraints system sensor is mine?
There is no generic answer, and any source that gives you one is guessing. The letter is assigned by the vehicle manufacturer, and the same letter refers to different physical components on different makes — sometimes on different model years of the same vehicle. The only authoritative source is the wiring diagram or service information for your exact year, make, model and body style.
A manufacturer-specific definition always outranks the generic one. If your make publishes its own meaning for this code, use that and ignore the generic description.