EngineLightCodes
Network code

U0170 Lost Communication with Restraints Front Sensor "B"

Severity
Fix soon
Typical repair cost
$110–$1,320
Do it yourself
Shop job
Shop time
1.0–4.0 hours

The Restraints Front Sensor "B" has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages.

How the engine computer detects it

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.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

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

Common causes

  1. Front sensor B unpowered Most likely
  2. Wiring to front sensor B broken Possible
  3. Gateway module routing CAN messages incorrectly Less likely

How to diagnose U0170

  1. Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
  2. Inspect the parts involved: restraints front sensor, can bus wiring.
  3. Work through the causes above from most to least likely, cheapest checks first.
  4. Clear the code and drive a full drive cycle to confirm the repair held.

Vehicles that report U0170 most

VehicleYearsReportsMedian miles
Pontiac G82008–20091172k
Cadillac ELR2014–20163—

Counts of owner complaints to the NHTSA that mention U0170 (17 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.

Reading the code

U
Network
0
Generic (SAE) code
170
Specific fault

Questions drivers ask

Can I drive with code U0170?

The car drives normally, but with the airbag light on some airbags or seatbelt pretensioners may not work in a crash. Get the system checked soon, and leave airbag parts to a shop: they can deploy and injure you.

Often reported together

Codes that owners mention in the same NHTSA complaints as U0170. They can point to a shared cause, so it's worth checking them together.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.