U017F: Lost Communication With Seat Belt Pretensioner Module B

What it means

ECU lost communication with seat belt pretensioner module B. Pretensioner function may be unavailable in a crash.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

Seat Belt Pretensioner Module B manages or reports a pretensioner function in the vehicle’s restraint system. U017F is set when the ECU misses Module B’s network messages for the required interval; lost module power, incorrect gateway routing, or a CAN termination fault can interrupt communication.

Common causes

Most likely first.

1. Module unpowered
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Airbag or restraint-system warning
• Pretensioner function associated with the module may be impaired
• Other communication codes

How to diagnose it

1. Scan all modules and review freeze-frame data to check whether U017F appeared with other restraint codes, network faults, or low voltage.
2. Use vehicle service information to locate Pretensioner Module B and inspect its connector and harness for corrosion, damage, loose pins, or disconnection.
3. Verify Module B power and ground against the manufacturer's specification.
4. Check gateway codes and determine whether communication loss affects other modules on the same network.
5. Test the CAN wiring and termination using the manufacturer's procedure.
6. If the module has correct power and ground and the network tests pass, test Pretensioner Module B using the manufacturer's restraint-system procedure.

Common fixes

• Repair the power or ground circuit supplying Pretensioner Module B.
• Clean and secure the module connector or repair damaged wiring.
• Correct a confirmed gateway routing or CAN network fault.
• Replace Pretensioner Module B if testing confirms it has failed.

Can I keep driving?

The belt pretensioner associated with Module B may not function in a crash, so have the restraint system checked promptly and drive cautiously. Avoid disturbing pretensioner wiring unless following the vehicle’s specified safety procedure.