OBD-II · Engine and powertrain (P)
P0600
Serial communication link
What it means
The ECU detects a fault in a serial communication link. Identify the affected link and modules from the vehicle's service information; the code does not by itself prove an internal ECU failure.
Symptoms
- engine warning light
- possible limp mode, stalling or no start
- sometimes no noticeable change
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | low or unstable module supply voltage or poor earth connections |
| 02 | open, shorted or corroded communication wiring/connectors |
| 03 | another control module failing to communicate or disrupting the link |
| 04 | water ingress into wiring or a module |
| 05 | internal module fault or software issue |
What to check, step by step
- 01Record faults from all accessible modules and identify missing modules or messages using OEM diagnostic information
- 02Check the battery, charging voltage and power supplies and earths of the affected modules
- 03Inspect the relevant communication wiring and connectors, then test the link using the OEM electrical procedure
- 04After repairing any supply or wiring fault, clear codes and verify communication
- 05Consider applicable software updates or module repair/replacement only after the link and module supplies pass testing; use stable programming power and required coding