U0248: Lost Communication With Remote Accessory Module
What to do
The car drives normally, and there may be no symptom at all beyond the stored code.
The first question is what has been connected to your vehicle, because this module exists specifically to serve add-on equipment — a tracker, a telematics or fleet box, a remote start system, accessory or upfitter wiring on a commercial vehicle.
Three things to think about:
- Is something fitted that might have failed? A misbehaving accessory can take this module down with it. Disconnecting the aftermarket equipment and re-checking is the fastest test there is, and if the fault clears, your vehicle is fine.
- Was something installed recently? Aftermarket wiring done badly — spliced into the wrong circuit, or earthed to a signal wire — produces faults that look like the car's own.
- Was something removed? A tracker taken out at the end of a lease, or telematics removed on sale, leaves this module expecting equipment that is no longer there. That gives a permanent code with nothing actually wrong, and the fix is a coding change rather than a repair.
What this code means
The remote accessory module has stopped being heard from. See U0200 for the block's framing.
This module is the vehicle's designated interface for equipment that was not fitted at the factory — upfitter connections on commercial vehicles, telematics and fleet tracking, remote start systems, accessory control, and on some vehicles the connection point for bodybuilder equipment.
It is therefore the one module in the whole block most likely to be the aftermarket's fault rather than the vehicle's, and that reframing is the point of this page. When any other module goes quiet, the vehicle's own wiring is the first suspect. Here, the first question is what has been connected to it, because that is what it is for.
Three patterns account for most of these.
Something plugged in has failed or is misbehaving, taking the module or its branch down with it — the corpus's standing point that one device can hold a network down applies with particular force to a connector designed for third-party equipment.
Something was installed badly. An accessory spliced into the wrong circuit, a ground taken from a signal wire, or a connector forced is ordinary on aftermarket work and produces faults that look like vehicle faults.
Or something was removed. A tracker taken out when a lease ended, a fleet telematics box removed on sale, a remote start uninstalled — and the module left configured to expect it. That produces a permanent code with no symptom whatsoever, and it is a coding correction rather than a repair.
So the diagnostic sequence here is unusual and worth stating: disconnect the aftermarket equipment first, then re-check. If the fault clears, the vehicle is fine.
Likely causes
Start here
- Faulty aftermarket alarm or immobiliser installation · moderate
- Module not coded to the vehicle · specialist
- Another module holding the bus down · specialist
- Corroded or loose connector · easy
Less common
- Damaged data bus wiring · moderate
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
Be the first to write this up
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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