OBD-II code family
Invalid Data Received From Gateway (U0447–U0451)
5 codes describing the same fault on 5 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
These codes sit one step beyond the Lost Communication gateway family, and the difference is the whole diagnosis. Lost Communication means a module heard nothing from the gateway. Invalid Data means it heard the gateway clearly and the message did not make sense — out of range, internally contradictory, failing a checksum, or contradicting what other modules are reporting about the same thing.
That matters because a gateway does not usually originate data. It relays it. So an implausible message arriving from the gateway often started somewhere else entirely: a sensor on the far side of the network is reporting nonsense, and the gateway is faithfully passing that nonsense along. The receiving module blames the messenger because the messenger is the last thing it heard from. This is why replacing a gateway on one of these codes so often changes nothing — the fault was upstream the whole time.
The letter A through E indexes which gateway on multi-gateway vehicles, with no generic meaning and no industry-standard mapping. Consult the wiring diagram for your specific vehicle.
The practical approach is to work outward rather than at the gateway. Read every stored code across every module, not just the one that set this code, and look for what the implausible value describes — a speed, a temperature, a position. Then find the module that originates that value and check whether it is healthy. Software mismatch is the other recurring cause: a module replaced or updated in isolation can end up speaking a slightly different dialect than the rest of the vehicle expects, and the symptom is data that arrives intact but does not agree with anything else. Check for outstanding reprogramming campaigns before condemning hardware.
Which received from gateway 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.