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DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0064

B0064Driver Seat Belt Tension Sensor

B0064 indicates that the body control module (BCM) or occupant restraint controller has detected a fault in the driver seat belt tension sensor circuit, which measures the force applied to the belt during a crash. The computer compares the sensor's voltage signal against expected limits and sets this code when the reading is out of range, erratic, or missing entirely.

SystemBody
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

  • The supplemental restraint system (SRS) warning light stays illuminated on the dashboard.
  • A chime or message may appear reminding you to buckle the driver seat belt even when it is fastened.
  • The airbag system may be disabled or default to a reduced deployment strategy, though this is not always obvious to the driver.
  • Often no symptoms besides the warning light, with the vehicle driving normally.
  • In some vehicles, the seat belt reminder light may flash or stay on continuously.
  • Remote start or other convenience features tied to the restraint system may be inhibited.

Common causes, most likely first

  1. A faulty driver seat belt tension sensor, which is typically integrated into the seat belt buckle assembly and can fail internally.
  2. Damaged or chafed wiring between the sensor and the body control module, often at the buckle pivot or under the seat where flexing occurs.
  3. Corroded or loose electrical connectors at the sensor or the module, especially in vehicles exposed to moisture or spills.
  4. A defective body control module or occupant restraint controller that misreads the sensor signal.
  5. A seat belt buckle that is mechanically damaged or contaminated, preventing the sensor from reading correctly.
  6. Aftermarket seat covers or objects trapped in the buckle mechanism that interfere with sensor operation.
  7. Low battery voltage or a charging system fault that causes erratic sensor readings and sets a false code.

How to diagnose and fix it

  1. Verify the code with a scan tool that can read body codes and check for any related codes in the restraint system.
  2. Inspect the driver seat belt buckle and sensor wiring for visible damage, corrosion, or loose connectors, and repair as needed.
  3. Measure the sensor's resistance or voltage at the connector and compare it to the manufacturer's specification to confirm sensor failure.
  4. Check the seat belt tension sensor signal at the body control module to rule out wiring faults between the sensor and module.
  5. If the sensor is faulty, replace the driver seat belt buckle assembly with the integrated sensor, following the manufacturer's procedure.
  6. Clear the code and perform a road test to verify the repair, ensuring the SRS light does not return.
  7. If the code persists after sensor replacement, diagnose the body control module or restraint controller for internal faults.

What the tension sensor actually does

  • The seat belt tension sensor is not the same as the seat belt buckle switch; the switch tells the module whether the belt is buckled, while the tension sensor measures how much force the belt exerts on the occupant.
  • A common misdiagnosis is replacing the seat belt buckle switch when the tension sensor is at fault, so always confirm which component the code refers to in the service information.
  • The tension sensor is part of the supplemental restraint system, and a fault can disable airbag deployment, so never ignore the warning light even if the car drives fine.
  • Wiring harness damage under the driver seat from seat movement or cargo is a frequent cause that is often overlooked during diagnosis.
  • After any repair, the restraint system may require a scan tool to re-enable the airbag circuit or clear crash data, depending on the vehicle.

Can I keep driving with B0064?

You can usually drive the vehicle with this code, but the airbag system may be compromised in a collision, so avoid aggressive driving and have the fault diagnosed promptly. Do not attempt to repair the restraint system unless you are trained, as improper handling can cause accidental airbag deployment.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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