P0600: Serial Communication Link Malfunction

Short answer: P0600 means “Serial Communication Link Malfunction”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 5 cars we cover, with a link to the full page for each car.

Standard OBD-II code Same meaning on all cars (SAE J2012).

P0600 on each car

Symptoms

1. Check engine light on
2. An inexperienced technician may begin by attempting to diagnose the affected system rather than the loss of communication. If the ECM is not…
3. ABS light illuminated
4. Transmission light illuminated (vehicle may not shift properly)
5. Big drop in fuel economy
6. Driveability problems may occur, such as stalling at an idle, rough running and poor acceleration, or

Likely causes

1. Experience has proven that a poor connection or failed ECM driver is the root cause of this code. For the most part, the ECM acts as a ground to…
2. A loose or corroded connector is more likely than a frayed or broken wire between both devices. Poor grounds are another plausible cause. The ECM,…
3. The wiring harness or Can Bus may be defective and have a short to ground or an open wire

What to check, in order

1. Check all battery and ECM power and earth connections first
2. Read every stored code; an ECM fault is rare, wiring faults are common
3. Have a specialist confirm before replacing the ECM

Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.

All fault codes