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U0172 Lost Communication With Restraints System Sensor C

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0172 marks a lost link to restraint sensor C. Chrysler uses it for the first left side satellite acceleration sensor in the Jeep tables of NHTSA file PE11-019. The Wrangler JK has just this one sensor on each side, whereas Compass/Patriot, Liberty, Grand Cherokee and Commander add a second left unit reported as U0173. Bosch fits side sensors of this type to load-bearing parts such as sills, seat cross members and the B- or C-pillar, because a side impact leaves almost no crush space and the airbag unit must decide within a few milliseconds. With sensor C missing, left side and curtain airbag deployment may be degraded. An internal fault of the sensor appears as B1B72 instead. Water in the footwell or seat removal are typical triggers. No MIL.

Likely causes

Water in the left footwell or sill area reaching the sensor connector
Connector disturbed during seat, carpet or trim removal
Left side satellite sensor failed after a side knock
Airbag control unit input or configuration faulty

Symptoms

  • Airbag warning lamp on
  • Left side and curtain airbag deployment may be impaired
  • Fault can be intermittent with wet carpets or after rain

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 ccrash signal wiring

Related codes

U0151U0170U0171U0173U0473

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