Parts
$50–1000
P0600 — Serial Communication Link Malfunction
CAUTIONIs it safe to drive? The ECM lost communication with one or more modules — don't ignore this; it can trigger cascading faults and in rare cases cause unexpected electrical behavior while driving.
What P0600 means
The ECM uses a controller area network (CAN bus) to talk to other modules (transmission, ABS, instrument cluster, body control). P0600 means that bus communication broke down. Can be a wiring fault, a failed module pulling the bus down, or the ECM itself.
Most likely causes (in order)
- Damaged CAN bus wiring (chafed, cut, or corroded — especially near connectors and bulkhead pass-throughs)
- Failed module shorted and pulling the CAN bus low (disconnect modules one at a time to find it)
- Poor chassis ground or main power ground
- Battery voltage low or unstable
- ECM connector corrosion or damaged pins
Symptoms you might notice
- multiple unrelated codes across systems
- instrument cluster errors
- transmission shift issues
- CEL and other warning lights simultaneously
What to check first
Check CAN bus resistance between CAN-H and CAN-L pins at the OBD-II port (pins 6 and 14) with the ignition off — should read 60 ohms (two 120-ohm terminating resistors in parallel). Significantly higher or lower means a bus wiring fault or a failed terminating resistor.
Repair cost & difficulty
Labor
1–6 hr
Difficulty
Advanced