U0434high severityNetwork
Invalid Data Received from Immobilizer Module
on 2002 Audi A4 3.0L V6 · AWD
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.
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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