AU
B17281B

DTC B17281B indicates the Supplemental Restraint System (SRS) detects the right knee airbag (front passenger knee airbag) igniter circuit resistance exceeds the normal threshold (typically >3 — Atto 3

Safety System

DTC B17281B indicates the Supplemental Restraint System (SRS) detects the right knee airbag (front passenger knee airbag) igniter circuit resistance exceeds the normal threshold (typically >3.5Ω; normal range 1.5-3.0Ω).

This open-circuit fault indicates high resistance or an open circuit in the airbag igniter circuit.

When the SRS control module detects continuously high resistance, it flags the airbag as abnormal, illuminates the airbag warning light, and disables deployment of the affected airbag.

During a collision, the right knee airbag may fail to deploy, disabling lower limb and pelvic protection for the front passenger and increasing the risk of injury.

The B17281B fault code on the Atto 3 indicates the SRS has detected high resistance or an open circuit in the front passenger right knee airbag igniter circuit. Severity is medium because this airbag may not deploy in a crash. Common causes include a loose or oxidized connector under the passenger-side dashboard, a backed-out pin, or an internal airbag igniter fault. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Loose knee airbag module connector, backed-out pin, or oxidized terminal: Located under the passenger-side dashboard. Cabin humidity or vibration increases contact resistance.
  • 2Airbag igniter internal open circuit or aging: A broken igniter bridge wire or oxidized resistance wire inside the airbag module causes increased resistance.
  • 3Wiring harness open circuit or localized damage: Poor connection, breakage, or water corrosion in the wiring harness from the SRS ECU to the right knee airbag, inside the instrument panel or at the floor harness junction.
  • 4SRS control module internal sampling circuit fault: ECU internal resistance detection circuit malfunction, incorrectly reading a normal resistance value as too high.
  • 5Improper reassembly after repair: Connector not fully locked or secondary locking clip not seated after replacing the instrument panel assembly or knee airbag.
What To Do
  • 1
    Use the BYD VDS diagnostic tool to read the DTC freeze frame data. Confirm the DTC status is Active, note the specific resistance value, and record the environmental data.
  • 2
    Disconnect the battery negative terminal and wait at least 3 minutes to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 3
    Remove the front passenger instrument panel lower trim and locate the right knee airbag module (usually below the glove box). Check that the airbag connector (yellow marking) is fully locked. Inspect the terminals for oxidation, backed-out pins, or signs of water ingress.
  • 4
    Replace the airbag module with a dedicated airbag tester or a simulator resistor (2Ω). Measure the circuit loop resistance to determine whether the fault is on the wiring harness side or the airbag module side. Never use a standard multimeter to measure the airbag igniter directly.
  • 5
    Disconnect the SRS control module connector and measure wiring harness continuity from the ECU to the airbag connector. Inspect the transfer connector between the instrument panel harness and the floor harness (usually located in the middle of the center console or below the A-pillar) for oxidation.
  • 6
    If the wiring harness is normal, replace the right knee airbag module and install new retaining clips. If the wiring harness is faulty, repair the wiring harness and apply waterproof insulation.
  • 7
    Reconnect all connectors and the battery. Clear the fault codes and perform an SRS system self-check (turn the ignition switch to ON and verify the airbag warning light turns off after 6 seconds). Finally, perform a crash simulation test (use the diagnostic tool to run the component test function to verify circuit integrity).
Real-World Cases
BYD DTC AI Analysis

Qin PRO DM: High resistance in right knee airbag after water wading

✓
A 2019 BYD Qin Pro DM owner reported the airbag warning light stayed on after driving in heavy rain. Retrieved DTC B17281B. Inspection found the front passenger carpet wet. Removing the right knee airbag revealed water in the connector and green oxidation on the terminals. Water entered behind the dashboard through the air conditioning intake while driving through water. The repair: cleaned and dried the wiring harness connector, replaced the right knee airbag module (as the internal igniter may have become damp), and applied dielectric grease to the connector. Fault resolved.
BYD DTC AI Analysis

Replaced instrument panel on Qin Pro, airbag warning light now on.

✓
2018 Qin Pro petrol variant. The day after a dealership replaced the instrument panel assembly, DTC B17281B appeared. Inspection revealed the technician hadn't fully seated the right knee airbag harness connector during installation—they pushed it all the way in but didn't hear it click, resulting in poor terminal contact. Fix: disconnected and reconnected the connector, confirming it locked into place (audible click). Cleared the fault codes and the resistance returned to 2.1 Ω. Problem solved.
BYD DTC AI Analysis

Intermittent high resistance after driving on rough roads

✓
A 2019 BYD Qin Pro DM had an intermittent airbag warning light on rough roads, normal on smooth roads. Diagnosis found an intermittent DTC; circuit resistance fluctuated between 2.8–4.2 Ω. Inspection revealed the right knee airbag wiring harness rubbing against the metal dashboard bracket. Prolonged friction wore through the insulation and partially fractured the copper wires, causing an intermittent connection. Repaired the harness, re-wrapped and rerouted it clear of the sharp bracket, and secured it with cable ties to prevent movement. Fault eliminated.
BYD DTC AI Analysis

SRS control module falsely reporting high resistance

✓
A 2018 Qin Pro had multiple right knee airbag resistance measurements all within normal range (2.0 Ω), but the diagnostic tool kept logging DTC B17281B and displaying a 5.2 Ω reading. Inspected wiring harness and found no faults. Suspected internal sampling circuit fault in the SRS control module. Substituted a known-good SRS module — fault code cleared. Repair: Replaced airbag control module (reprogramming required to match VIN and configuration). Fault resolved.
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For the BYD Song MAX (2017–2019), DTC B1108 indicates a short circuit in the PM2.5 air quality detection module (dust sensor) or its wiring harness. The sensor uses laser scattering to detect in-cabin and outside PM2.5 concentrations and transmits data to the HVAC ECU via the LIN bus or an analog signal. Short circuit conditions include: 1) Sensor power supply wire (+5V/+12V) shorted to ground 2) Signal wire shorted to power or ground 3) Short circuit in the sensor's internal photoelectric detection circuit This fault prevents the automatic climate control from switching between fresh air and recirculation based on air quality. The system enters fail-safe mode (typically forced recirculation). Severe short-circuit current can destroy the HVAC ECU sampling circuit. The system classifies this as a Level 3 severe fault and restricts vehicle operation to prevent electrical fires or controller damage. For other BYD models (such as the Qin EV, E5, and Song DM), B1108 indicates a driver-side sunload sensor fault, reflecting differences in DTC definitions across models.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
Common problems reported for Atto 3 →Atto 3 overview →
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.