P0600high severityPowertrain
Serial Communication Link
on 2021 Mazda Mazda3 2.0L I4 · AWD
What this code means
Malfunction in the serial data communication link between the PCM and other modules.
Symptoms
- Check Engine Light
- Multiple warning lights
- Communication errors on scan tool
- Some modules not responding
Common causes
- Faulty CAN bus wiring
- PCM failure
- Module failure on bus
- Terminated resistor issue
- Aftermarket device interfering with bus
Diagnostic steps
- Check for aftermarket devices on OBD-II port
- Test CAN bus wiring
- Check bus termination resistors
- Scan all modules for communication
- Inspect wiring for damage
Repair notes
Check for aftermarket devices first. Then check CAN bus wiring. PCM replacement is rare.
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