U0434high severityNetwork
Invalid Data Received from Immobilizer Module
on 2004 Ford Taurus 3.0L V6 Duratec · FWD
What this code means
Data from the immobilizer or anti-theft module is invalid, preventing vehicle operation.
Symptoms
- Vehicle will not start
- Security indicator flashing
- Key not accepted
- Cranking but no fuel/spark
- Immobilizer fault message
Common causes
- Key transponder weak or failing
- Antenna ring malfunction
- Immobilizer module corruption
- CAN bus interference
- Key not properly programmed
Diagnostic steps
- Test key transponder signal strength
- Check antenna ring signal
- Attempt key relearn procedure
- Check CAN bus quality at immobilizer module
- Test with known good key
Repair notes
Attempt key relearn procedure. If key transponder is weak, program new key.
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