Modules on the CAN bus cannot talk to each other reliably. Expect several warning lights at once and features that stop working for no obvious reason.
P0600 — also written PO6OO, P 0600, 0600 — is the OBD-II code for serial communication link malfunction. Same code, same fix: this page covers every spelling of it.
P0600 is a electrical fault code, typically costing £90–£900 to put right in a UK garage.
What causes P0600?
- Corroded or water-damaged connector on the bus
- Chafed CAN wiring
- One failed module dragging the bus down
- Poor earth
How P0600 is fixed
- Read fault codes from every module to find the one that has dropped off
- Inspect the loom at flex points and door harnesses
- Repair earths and connectors before replacing any module
P0600 repair cost in the UK
Most P0600 repairs land between £90–£900 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Can you drive with P0600?
Depends on which systems are affected — drive with caution and get it scanned promptly.
Urgency: high.
What P0600 is telling you
Electrical faults of this type are proved with a meter, not a parts catalogue. Supply, signal and earth are each tested at the connector before anything is ordered.
On P0600 specifically — serial communication link malfunction — the stored code records the moment that check failed, not the moment the part gave up. That gap is why two cars with the same code can need completely different repairs.
How P0600 is diagnosed properly
Each of the known causes is ruled in or out in cost order, cheapest and most likely first. On P0600 that means working through them like this:
- Corroded or water-damaged connector on the bus — opened, inspected for green corrosion and spread pins, and back-probed rather than unplugged, so the reading is taken with the circuit live.
- Chafed CAN wiring — checked with the loom flexed and the engine warm, because a wiring fault that is intermittent when cold shows itself under heat and vibration.
- One failed module dragging the bus down — checked for outstanding manufacturer updates before any hardware is touched.
- Poor earth — confirmed with live data before any part is bought.
An hour of diagnostic time on P0600 routinely saves more than it costs, because the alternative is buying the most expensive part on that list and hoping.
The repairs that actually clear P0600
- Read fault codes from every module to find the one that has dropped off
- Inspect the loom at flex points and door harnesses
- Repair earths and connectors before replacing any module
After the repair the code is cleared and the car is driven until the relevant readiness monitor completes, rather than handed back as soon as the light goes out. A code that has only been erased will come straight back on the next drive cycle.
What happens if P0600 is ignored
Leaving this one is the expensive choice. The protection strategy the ECU falls into is there to limit damage, and every mile driven with the fault active is a mile the engine or gearbox spends outside its designed operating window.
For reference, P0600 typically lands at £90–£900 all-in at an independent garage in the UK — main-dealer quotes for the same job usually sit above that.
Getting P0600 looked at
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0600 is showing on your car, bring the scan results with you — we will read the live data ourselves, tell you which of the causes above it actually is, and price the repair before any work starts.