Summary
P0600 means the PCM has detected an internal serial communication error — either within its own internal processors or on the communication bus between the PCM and other control modules. The most common causes are a PCM power or ground problem (30%), corroded or damaged CAN bus wiring (25%), and a failing PCM (20%). This code often requires professional-level diagnosis with advanced scan tools.
Severity: High — various driveability issues possible
Safe to drive: No — unpredictable driveability problems; diagnose immediately
Repair cost: $100–$1,500 depending on cause
DIY difficulty: Hard
What does P0600 mean?
Modern vehicles use a controller area network (CAN bus) — a serial communication system that allows the PCM and dozens of other modules (transmission control module, ABS module, body control module, etc.) to share data. The PCM also has internal communication between its own processor cores and memory.
P0600 is set when the PCM detects a failure in this serial communication. This can mean the PCM's internal processors cannot communicate with each other (internal fault), the CAN bus has a communication error (wiring or termination fault), or a module on the network is corrupting the data bus.
The symptoms of P0600 vary widely depending on which communication pathway is affected. You may experience no symptoms at all, or you may have hard starting, stalling, erratic idle, transmission shifting problems, inoperative gauges, or multiple warning lights illuminated simultaneously. Because so many systems depend on the communication network, the effects can be unpredictable.