P0600: Serial Communication Link
What to do
Often driveable, sometimes with reduced performance or a gearbox stuck in a default mode. Ask for a full scan of every module rather than just the engine — which module has gone quiet is the diagnosis, and it will not appear in an engine-only scan.
What this code means
A module has lost or corrupted communication with another module. Modern vehicles are networks: the engine, transmission, ABS, body and instrument modules exchange hundreds of messages a second, and most of them assume the others are answering.
When they are not, the symptoms scatter. A transmission that cannot hear engine load will default to a safe shift pattern; an instrument cluster that cannot hear road speed shows nothing. So the presenting complaint is rarely where the fault is, and a scan of every module rather than just the engine is the necessary first step — the module that is silent tells you far more than the modules complaining about its silence.
A single damaged wire in the bus, a corroded connector, or one module holding the network down electrically will all do it. That last case is worth knowing: a failed module can prevent every other module communicating, so a bus that is completely dead often has one bad participant rather than a broken cable.
Likely causes
Start here
- Damaged network wiring · specialist
- Corroded or loose connector · easy
- Failed control module · specialist
Less common
- Low system voltage disrupting communication · moderate
- Water ingress into connector · 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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