P0600: The engine computer has a communication network fault
Serial Communication Link Malfunction
The engine computer lost communication with another module. Get it checked as soon as you can. If it will not start, stalls, misfires or shows warnings across several systems, have it towed.
Stop driving and get help if
- The check engine light is flashing
- The temperature gauge runs high, or you see steam (overheating)
- The car loses power, hesitates badly or stalls
- You smell burning or see smoke
- A brake warning light comes on, or the brakes feel different
Pull over as soon as you can, turn the engine off, and call a tow or roadside help.
What it means
Modern vehicles have multiple computers talking to each other over a CAN bus network. P0600 means there is a fault in that communication link. This is a broad code that does not identify which module has stopped communicating or why. It can accompany dozens of other codes. The practical meaning is that one or more modules are not able to share data reliably. Wiring integrity to the CAN bus, battery voltage, and corroded ground connections are the most common physical causes. A jump-start with dead batteries is a known trigger on some platforms.
Common causes
- Damaged or shorted CAN bus wiringThe two CAN bus wires can short together or to ground, disrupting all module communication.
- Corroded or loose battery connections and ground strapsLow or unstable voltage disrupts CAN communication. Check ground straps to chassis and engine.
- Failed module pulling the bus downOne defective module can bring down communication for all others on the same bus.
- PCM or TCM failureThe primary controller itself has failed. Requires professional diagnosis to confirm.
What the fix could involve
From the cheaper fix to the bigger one. Prices depend on your car, your area and the shop, so ask for a written quote that names the part and the labor before you approve it.
- Battery and grounds inspection and repair
- CAN bus wiring repair
- Module replacement (varies by which module)
Symptoms
- Multiple warning lights across different systems
- Erratic instrument cluster readings
- Transmission shift problems
- Engine performance issues
- Non-responsive controls
What to do next
This code requires a scan tool that can read CAN network activity, not just generic OBD codes. Bring it to a shop with factory-level diagnostic capability. Before paying for module replacement, have the technician verify battery voltage, all ground connections, and CAN bus wire integrity. Module replacements are expensive and often require programming.
Lewis reads codes from every computer it can reach on your car in one scan, which helps a technician see whether other modules logged communication faults at the same time. Get Lewis on the App Store or Google Play.
Related codes
FAQ
- Can a bad battery cause P0600?
- Yes. Low or unstable voltage disrupts CAN communication. Check battery voltage and grounds before assuming a module has failed.
- Will clearing the code fix it?
- No. Clearing codes is not a repair. The communication fault is still there and will return immediately.
- How serious is this compared to other engine codes?
- It is one of the more serious codes because it can affect every system on the vehicle simultaneously. Get it diagnosed promptly.
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