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U0171 Lost Communication With Restraints System Sensor B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0171 says the airbag control unit receives nothing more from restraint sensor B. Chrysler documents it as the up-front right satellite acceleration sensor, the mirror image of U0170, in each Jeep airbag listing it supplied for investigation PE11-019, starting with the 2007 Wrangler; an internal defect of that unit is logged separately as B1B71. Front satellites of this kind sit inside the crumple zone. Bosch notes that they sharpen frontal crash detection beyond what the sensors inside the central unit can do, so without B the decision for the right half rests on less information. The location is exposed to spray, salt and collision damage, so after front-end body work an unplugged or wet connector is the first suspect. Other makes may give B another position. Airbag lamp on, no MIL.

Likely causes

Connector of the right front sensor not reconnected after bumper or front-end work
Water or road salt in the sensor connector at the front
Front satellite sensor B damaged in a collision
Sensor line to the airbag unit open or shorted

Symptoms

  • Airbag warning lamp on
  • Frontal impact sensing on the right side relies on the central unit only
  • Code comes back immediately after clearing while the fault persists

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

restraints system sensor bcrash signal wiring

Related codes

U0151U0170U0172U0472

References: static.nhtsa.gov, bosch-mobility.com.