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DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0028

B0028Driver Side Curtain Air Bag Deployment Control

B0028 indicates that the supplemental restraint system (SRS) control module has detected a fault in the deployment circuit for the driver-side curtain air bag, which is the inflatable cushion that drops from the roofline to protect the driver's head in a side impact. The computer monitors the circuit's resistance and continuity and sets this code when the readings fall outside the expected range, disabling that air bag to prevent an accidental deployment.

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

Symptoms you may notice

  • The air bag warning light on the instrument cluster stays illuminated after the bulb check
  • A message such as 'Service Air Bag' or 'SRS Fault' appears in the driver information center
  • The driver-side curtain air bag will not deploy in a side impact or rollover event
  • Often no symptoms besides the warning light, with the vehicle driving normally
  • Other SRS codes may be stored alongside B0028 if the fault affects shared wiring

Common causes, most likely first

  1. Damaged or chafed wiring in the driver-side curtain air bag circuit, often where the harness passes through the A-pillar or roof header
  2. Loose, corroded, or unseated electrical connector at the curtain air bag module or at the SRS control module
  3. Failed clock spring or spiral cable in the steering wheel, which can affect driver-side SRS circuits on some vehicles
  4. Internal fault in the driver-side curtain air bag inflator or module
  5. Water intrusion or corrosion in the connector or wiring caused by a leaking sunroof drain or roof seam
  6. Faulty SRS control module that incorrectly reports the circuit resistance
  7. Aftermarket accessories or previous repairs that disturbed the air bag wiring

How to diagnose and fix it

  1. Inspect the driver-side curtain air bag connectors at the module and at the SRS control module for looseness, corrosion, or bent pins, and reseat them firmly
  2. Check the wiring harness along the A-pillar and roof header for chafing, pinches, or damage from previous trim removal
  3. Measure the resistance of the curtain air bag squib circuit with a digital multimeter and compare it to the manufacturer's specification
  4. Perform a wiggle test on the harness and connectors while watching live SRS data to see if the fault changes
  5. If resistance is out of range, isolate the air bag from the harness and recheck to determine whether the module or the wiring is at fault
  6. Replace the faulty component, such as the curtain air bag module, clock spring, or damaged harness section, following the manufacturer's procedures
  7. Clear the codes and verify the repair with a scan tool that can read SRS data and confirm the warning light stays off

Before you replace the curtain air bag

  • A loose connector or chafed wire behind the A-pillar trim is far more common than a failed air bag module, so always inspect the harness before condemning the bag.
  • This code does not always mean the air bag itself is defective; a fault in the SRS control module or its power and ground circuits can set the same code.
  • Water leaks from a clogged sunroof drain or roof seam can corrode the curtain air bag connector and trigger B0028 without any visible damage.
  • Disconnecting the battery and waiting the recommended time is mandatory before working on any SRS circuit, because a stray voltage can deploy the air bag.
  • Some vehicles require the SRS module to be configured or the new air bag module to be registered with a scan tool after replacement, or the code will return.

Can I keep driving with B0028?

The vehicle remains safe to drive in normal conditions because the affected air bag is disabled, but you should avoid any situation that could produce a side impact or rollover until the fault is repaired. Have the system diagnosed promptly, since the driver-side curtain air bag will not protect you in a crash.

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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