U0493: Invalid Data Received From Personal Computer
What to do
On an ordinary private car, this almost certainly is not a fault.
This code refers to a working computer carried by the vehicle and plugged into its network — a police car's data terminal, an ambulance's records system, a taxi's dispatch unit, a delivery van's routing terminal. Private cars do not have them.
So if you see this on a normal car, it is most likely either a coding leftover — from a second-hand module that came out of a fleet vehicle — or an aftermarket device that has been wired in, such as an insurance tracker or a fleet box. Nothing on the car has broken. Mention any such device; removing or correcting it is the fix.
If your vehicle genuinely has one of these terminals, go back to whoever installed it before going to the car's dealer. They designed the connection to the vehicle, and that is nearly always where the fault is.
One thing worth raising in that case: does the vehicle's battery go flat when it stands over a weekend? A terminal that keeps reading the network when the vehicle is parked stops it going to sleep, and that is the commonest real problem behind this code.
What this code means
The on-board computer module is broadcasting data that cannot be accepted as true. See U0400 for the family's framing.
The standard reserves a place for a general-purpose computer carried by the vehicle, and it is worth being clear about what that means, because it is not the vehicle's own control modules.
It is a working computer belonging to whoever operates the vehicle, connected to the vehicle's network so that it can read speed, position, doors, fuel and equipment state. That is the mobile data terminal in a police car, an ambulance's patient record system, a taxi's dispatch unit, a delivery fleet's routing and proof-of-delivery terminal, a survey vehicle's data logger, or a driving school's assessment kit.
On a private car it is effectively never fitted, which gives the two things worth knowing:
- If this appears on an ordinary vehicle, it is almost certainly coding or an aftermarket installation — a fleet or insurance device wired in, or a second-hand module carrying a fleet configuration. Nothing on the vehicle has failed.
- If it appears on a working vehicle where such a terminal genuinely exists, the vehicle manufacturer's dealer is usually the wrong place to take it. The equipment was installed by a specialist, its connection to the vehicle network is their design, and the fault is nearly always at that join — a spliced connection, a shared earth, a device that keeps the network awake, or software on the terminal that no longer matches the vehicle after an update.
One further note that matters for the fleet case. A terminal that reads the vehicle network continuously must let the vehicle sleep when it is parked, and one that does not will flatten the battery over a weekend. That is the commonest real fault behind this code, and it is a fault in the installation rather than in the vehicle.
Likely causes
Start here
- Poor wiring splice in an aftermarket installation · moderate
- Module not coded to the vehicle · specialist
- Another module holding the bus down · specialist
Less common
- Corroded or loose connector · easy
- Software updated on one module only · specialist
- 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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