Cause
Faulty gateway module
The module that connects the vehicle's separate networks to each other has genuinely failed — which is worth putting last on a suspect list rather than first, because a gateway originates almost nothing.
A vehicle runs several networks at different speeds: a fast one for the powertrain, a slower one for body electrics, a cheap single-wire network for switches and motors, and often a separate high-bandwidth one for entertainment. They cannot talk to each other directly, so every message crossing between them passes through the gateway. It repeats and translates; it rarely has an opinion of its own.
So a gateway blamed for invalid data is usually relaying invalid data faithfully, and the fault is on the far side of it. The genuine gateway fault has a different signature, and it is a change rather than a decay: a software update applied to one module and not this one, a module added or removed, a coding change, a retrofit.
Two things make a real gateway problem recognisable. Breadth — warnings appear in systems with nothing in common, which reads as a catastrophe and is one module. And the diagnostic socket, which on practically every vehicle built this century is wired to the gateway rather than to the buses. A tool that connects to some modules and not others, or times out on the whole vehicle, is the one symptom nothing else produces — and it is what makes the fault awkward, because the instrument that would explain it is speaking through the thing that is wrong.
One further consequence is the expensive one to miss. The gateway is normally among the modules deciding when the vehicle may sleep, so one that will not settle flattens a healthy battery in a few days.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
1 of the 13 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (13)
Codes where this is a likely explanation first, rather than merely a possible one.
- U0001 High Speed CAN Communication Bus Stop driving High
- U0028 Vehicle Communication Bus A High
- U0037 Vehicle Communication Bus B High
- U0044 Vehicle Communication Bus B (-) High High
- U0055 Vehicle Communication Bus D Moderate
- U0146 Lost Communication With Serial Data Gateway Module A High
- U0147 Lost Communication With Serial Data Gateway Module B Moderate
- U0200 Lost Communication With Door Control Module B Low
- U0431 Invalid Data Received From Body Control Module A High
- U0447 Invalid Data Received From Serial Data Gateway Module A High
- U0448 Invalid Data Received From Serial Data Gateway Module B Moderate
- U0449 Invalid Data Received From Serial Data Gateway Module C Moderate
- U0451 Invalid Data Received From Serial Data Gateway Module E Moderate
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.
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Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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