OBD-II code · Network
U0170 Lost Communication with Restraints Front Sensor "B"
The Restraints Front Sensor "B" has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages. A front crash sensor is unreachable, affecting airbag timing. Safety-critical. Typical causes are loss of power or ground at the module, an open or shorted CAN/LIN bus wire, a connector fault, or an internal module failure.
Is it safe to drive with U0170?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyFront sensor B unpowered
- PossibleWiring to front sensor B broken
- Less likelyGateway module routing CAN messages incorrectly
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
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Restraints Front Sensor, Can Bus Wiring
Related codes
- U016BLost Communication With A/C Compressor Control Module
- U016CLost Communication With Fuel Pump Control Module B
- U016DLost Communication With Exhaust Gas Sensor Module B
- U0171Lost Communication with Restraints Rear Sensor "A"
- U0172Lost Communication with Restraints Rear Sensor "B"
- U0173Communication Bus "C" Off
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.