U0401moderate severityNetwork
Invalid Data Received from ECM/PCM
on 1997 Mazda Protege 1.5L I4 · FWD
What this code means
The data received from the PCM is invalid or corrupted.
Symptoms
- Various warning lights
- Erratic system behavior
Common causes
- PCM software issue
- CAN bus noise
- PCM failure
- Wiring interference
Diagnostic steps
- Update PCM software
- Check for TSBs
- Test CAN bus signal quality
- Check for electromagnetic interference
Repair notes
Reprogram PCM. Check CAN bus.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0004
High Speed CAN Communication Bus (+) Low
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0007
High Speed CAN Communication Bus (-) Low
U0008
High Speed CAN Communication Bus (-) High
U0009
High Speed CAN Communication Bus Shorted Together
U0010
Medium Speed CAN Communication Bus