P0600 OBD-II: Serial Communication Link

What Does P0600 Code Mean?

OBD-II Code P0600 is defined as a PCM Serial Communication Link Malfunction

The PCM or Power Train Control Module performs many vital functions in a modern vehicle, such as management of the Fuel System, Ignition System, Transmission, Anti-Lock Brake and Traction Control systems. The Serial Communication Link enables the control modules to 'talk ' to each other.

When the code P0600 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM has lost communication with 1 or more other control modules.

P0600 Symptoms

• Check Engine Light will illuminate
• ABS/Traction Control Light may illuminate
• Transmission Light May Illuminate
• Vehicle may not perform and/or shift properly
• Decrease in fuel economy
• In some cases, there may be performance problems, such as dying when coming to a stop and/or misfire-like symptoms
• In unusual cases, there are no adverse conditions noticed by the driver

Common Problems That Trigger the P0600 Code

• Defective PCM (Power Train Control Module )
• Defective PCM data bus wiring/connections
• Defective PCM data bus ground circuit(s)
• Defective PCM or other control module controlled output devices
• Defective CAN bus communication

Common Misdiagnoses

• Ignition problems whose root cause is a defective PCM
• Fuel Injection problems whose root cause is a defective PCM

Polluting Gases Expelled

• HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
• CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
• NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog

P0600 Diagnostic Theory for Shops and Technicians

The PCM shares data input with several different systems and if the communication link between them fails, then 1 or more systems will shut down. The cause of the P0600 code may be a defective data bus, a defective data bus connection, or a defective control module. If you have to replace a module, make sure that you inspect all of the module's output devices and wiring for shorted circuits or else the new module will fail in short order. When diagnosing a P0600 code, it is important to record any other codes and the P0600 freeze frame data. Then one should duplicate the code setting conditions with a test drive. Pay close attention to the engine load, throttle position, RPM, and road speed because a P0600 can be difficult to detect.