U0448: Invalid Data Received From Serial Data Gateway Module B
What to do
Expect connected features to stop working — the phone app, live traffic, hands-free calling, online services — while the car itself drives normally.
That combination is deliberate. On many modern vehicles this second gateway sits as a deliberate barrier between the parts of the car that can be reached from outside — telematics, keyless entry, phone and media connections — and the parts that steer, brake and drive it. When it stops passing messages, the connected features go and the car keeps working. That is the design doing its job.
One thing genuinely worth mentioning: any aftermarket tracker, dashcam, insurance box or plug-in dongle that has been fitted. This is exactly where such things get wired in, because it is where the useful data crosses, and a poor installation is a common cause of this code.
The car is normally safe to drive. If an emergency-call or breakdown-assistance service is part of what has stopped working, treat that as a reason to get it looked at sooner rather than later.
What this code means
A second gateway module is broadcasting data that cannot be accepted as true. See U0447 for what a gateway does and why invalid data from one is usually invalid data that reached it.
Why a vehicle would have two gateways is the interesting part, and one of the reasons is quite modern.
The ordinary reason is traffic. A vehicle with many networks — a large SUV, a commercial chassis with a body-builder interface, anything with a trailer control system — has more crossings than one module conveniently handles, so the work is split.
The other reason is security, and it is worth understanding. A vehicle now contains modules with radios in them: telematics, keyless entry, tyre pressure sensors, phone and media connections, over-the-air updates. Those modules can be reached from outside the vehicle, and the ones that steer, brake and drive it must not be. So a second gateway is often placed deliberately between the two groups, passing only the messages that are supposed to cross and refusing everything else. It is a boundary rather than a convenience.
That explains the symptom pattern where it applies. A fault on the outward-facing side takes out connected services, app functions, live traffic and hands-free calling while the vehicle drives entirely normally — which is exactly what the separation was designed to achieve, and is a good outcome rather than a bad one.
A caution that follows directly: this is the module an aftermarket tracker, dashcam or telematics dongle is most often spliced into, because it is where the useful data crosses. A poor installation here is a common and entirely avoidable cause.
Likely causes
Start here
- Poor wiring splice in an aftermarket installation · moderate
- Corroded or loose connector · easy
- Software updated on one module only · specialist
Less common
- Damaged data bus wiring · moderate
- Faulty gateway module · specialist
- Module not coded to the vehicle · specialist
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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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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