U0171 code meaning
Lost Communication With Restraints System Sensor B
What U0171 means
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.
U0171 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0171
- 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
Common causes of U0171
- Most likelyConnector of the right front sensor not reconnected after bumper or front-end work
- PossibleWater or road salt in the sensor connector at the front
- PossibleFront satellite sensor B damaged in a collision
- Less likelySensor line to the airbag unit open or shorted
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Restraints system sensor bCrash signal wiring
What each part of U0171 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 71 | The exact fault in that area. |
What to do next
- Note U0171 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0171
What does U0171 mean?
U0171 means "Lost Communication With Restraints System Sensor B". U0171 says the airbag control unit receives nothing more from restraint sensor B. It is a generic code, so it means the same on every make.
Is it safe to drive with U0171?
U0171 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0171 fail an emissions test?
U0171 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0171 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will U0171 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.