P0600: Serial communication link fault

What P0600 means

The car’s control units share data over a wired network. This code means the engine ECU has lost or cannot make sense of that communication with another unit. It can be as simple as a low battery or a loose plug, or an internal fault in one of the units.

Most common causes

• Low battery or poor terminal contact
• Plug on a control unit loose, wet or corroded
• Network wires chafed or broken
• Poor earth on one of the control units
• Internal fault in the engine ECU or another unit

Symptoms

• Engine warning light on
• Several warning lights at once on the dashboard
• Automatic gearbox or traction control in limp mode
• Sometimes hard starting or lack of power

Can you drive with P0600?

With care Some systems may be running in limp mode. Drive gently and get it to a garage soon.

How to check it

Note which other codes appear at the same time, especially any starting with U, as they show which unit is not responding. Also check the battery voltage on the scan tool.

How to read and clear P0600 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0600 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P0601 Internal control module memory checksum error
• P0602 Control module programming error
• P0603 Internal control module keep alive memory (KAM) error
• P0604 Internal control module random access memory (RAM) error
• P0605 Internal control module read only memory (ROM) error
• P0606 ECM/PCM processor fault
• P0607 Control module performance
• P0615 Starter relay: circuit fault

P0600 is a generic code, so it means the same on any make, for example on Audi, BMW, Fiat, Mazda, Peugeot, Volkswagen. See what Final OBD does on your car in makes and models.