OBD-II code · Network
U0409 Invalid Data Received from Vehicle Security Control Module
The vehicle security / alarm controller is sending implausible status data (e.g. armed/unarmed jitter). Alarm and immobilizer behaviour can become unpredictable.
Is it safe to drive with U0409?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- PossibleSecurity module internally failed
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- Parts involved
- Vehicle Security Module
Related codes
- U0427Invalid Data Received from Vehicle Security Control Module
- U0406Invalid Data Received from Cruise Control Front Distance Range Sensor
- U0407Invalid Data Received from Steering Angle Sensor Module
- U0408Invalid Data Received from Vehicle Immobilizer Control Module
- U040AInvalid Data Received From Air Conditioning Control Module
- U040BInvalid Data Received From Exhaust Gas Recirculation Control Module A
- U040CInvalid Data Received From Exhaust Gas Recirculation Control Module B
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.