Computer & output circuits · Powertrain · generic (SAE-defined)
P0600: Serial Communication Link
P0600 means the engine computer detected a fault in a serial data link it uses to exchange information with another control module or with an internal processor.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0600 sets
The powertrain control module (PCM) constantly exchanges messages with other modules, and on some designs between two processors inside the PCM itself. When expected messages stop arriving, arrive corrupted, or fail an integrity check for a set period, the PCM logs P0600. What counts as a fault, and which link is monitored, is manufacturer-specific.
Common causes of P0600
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Weak battery or low charging-system voltage
- Poor PCM ground or power supply connection
- Corroded or loose connector at the PCM or another module
- Damaged or shorted data-network wiring
- Failed module on the network pulling the bus down
- Internal PCM fault
- PCM software issue needing a reflash
P0600 symptoms
- Check engine light on
- Additional network (U-code) or module codes stored
- Erratic shifting or transmission in limp mode
- Traction control or ABS warning lights
- Stalling, hesitation or no-start on some vehicles
How P0600 is diagnosed
- Scan all modules, record freeze frame data and note every U-code and module fault stored
- Test the battery and charging system; a low-voltage event can set communication faults
- Inspect PCM power and ground circuits with a voltage-drop test under load
- Inspect network wiring and connectors for corrosion, chafing or water intrusion
- Check which modules are responding to the scan tool to isolate a silent module or bus fault
- Check for manufacturer service bulletins or PCM software updates before condemning the module
Typical fixes for P0600
- Repair or replace the battery, charging-system components or battery cables
- Clean and secure PCM grounds and power feeds
- Repair damaged network wiring or connectors
- Reprogram the PCM with updated software
- Replace the faulty module and program it to the vehicle
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Definitions can vary by manufacturer; on some vehicles P0600 refers to communication between processors inside the PCM, so check factory service information.
Related codes & warning lights
P0600 FAQ
What does code P0600 mean?
P0600 means the engine computer detected a fault in a serial data link it uses to exchange information with another control module or with an internal processor. The standard definition is "Serial Communication Link."
Can I drive with a P0600 code?
Usually for a short distance, but carefully. Because modules may stop sharing data, shifting, traction control or engine power can be affected without warning, so diagnose it within days.
Is P0600 always a bad computer?
No. Low system voltage, poor grounds and network wiring faults are frequent causes. The module should only be replaced after power, grounds and wiring check out.
Why do I have U-codes along with P0600?
U-codes are network communication codes. Seeing them together with P0600 points toward a data-link problem rather than a sensor fault, and the U-codes help show which module stopped talking.
Keep researching
More computer & output circuits codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.