AU
B173712

DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS) — Seal U

Safety System

DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS).

Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat.

The "12" suffix indicates a circuit short to battery positive (B+).

This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode.

This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1A damaged right middle-row side airbag wiring harness or aged insulation chafes against the body power wiring harness, causing a short circuit. This typically results from vehicle wading, underbody scraping, or incorrect harness routing during vehicle modification.
  • 2Bent pins, backed-out pins, or corrosion from water ingress at the airbag connector (usually located under the seat or inside the B-pillar trim panel), causing a short circuit between the ignition circuit terminal and the power supply terminal.
  • 3Internal short circuit in the SRS clock spring or insulation failure between coil windings, causing a short to power in the steering wheel or seat side airbag circuit.
  • 4Internal squib short circuit in the right middle row side airbag module. This condition is rare; if it occurs, replace the entire airbag module.
  • 5The vehicle experienced a previous side collision. The airbag did not deploy, but the impact crushed and deformed the wiring harness. Alternatively, improper securing of the wiring harness during accident repairs caused it to rub against the power cable, resulting in a short circuit.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment and personal injury.
  • 2
    Visual inspection: Remove the right B-pillar lower trim panel or seat side trim panel. Check the right middle-row side airbag connector (usually a yellow plug) for looseness, water ingress, corrosion, or foreign objects. Check the wiring harness for obvious damage or crush marks.
  • 3
    Circuit measurement: Use a multimeter to measure the voltage between the airbag connector terminal and body ground. The normal value is 0 V. Check continuity to the positive power supply terminal; the normal resistance is infinite. A reading of 12 V or continuity confirms a short circuit to power.
  • 4
    Step-by-step diagnosis: Disconnect the airbag module connector and measure the voltage on the harness side at the control unit. If voltage remains, the fault is in the wiring harness or connector. If voltage disappears, the fault is in the airbag module.
  • 5
    Wiring harness repair: If damaged, rewrap the wiring harness with high-temperature tape (Kapton tape). Replace the entire airbag wiring harness if necessary. Never use standard electrical tape or simple twisted splices to repair the airbag circuit.
  • 6
    Component replacement: If an internal short circuit in the airbag module is confirmed, replace the right second-row side airbag module. If the clock spring is faulty, replace the clock spring. After replacement, use the dedicated diagnostic tool to clear the fault codes and write the system configuration.
  • 7
    Final verification: Reconnect all connectors, restore power, and start the vehicle. Confirm the SRS warning light turns off after the self-check. Use the diagnostic tool to read the data stream and confirm the right middle row side airbag resistance is within the normal range of 2.0-3.0 Ω.
Real-World Cases
BYD DTC AI Analysis

Chafed wiring loom on right-hand second-row side airbag caused a short circuit in Qin EV

✓
A 2019 BYD Qin EV with 85,000 km had the airbag warning light on steady. Scanning pulled DTC B173712. The technician found the wiring harness retaining clip below the right B-pillar had come loose, letting the harness chafe against the seat rail. The friction wore through the insulation, and the exposed copper wires shorted against the seat heater power line. Repair steps: fixed the damaged harness, re-secured the routing, and added anti-chafe sleeving. After clearing the code, the system returned to normal; resistance measured 2.4 Ω.
BYD DTC AI Analysis

BYD E2 seat side airbag connector corroded by water ingress

✓
The airbag warning light came on in a 2020 BYD E2 after wading through water. The diagnostic tool showed B173712. Inspection found obvious water stains and verdigris corrosion inside the yellow airbag connector under the right front seat, causing an insulation-failure short circuit between the ignition circuit terminal and the seat memory power terminal. Water entered beneath the seat from the carpet while wading. Fix: Thoroughly cleaned the connector, flushed it with electronic cleaner, dried it, and applied conductive grease. Because the pins were corroded and deformed, replaced the wiring harness connector with a new one, which resolved the fault.
BYD DTC AI Analysis

E3 passenger side airbag module internal short circuit replacement case

✓
2020 BYD E3 developed DTC B173712 following accident repairs. Repair history indicated a collision to the right side; the side airbag had not deployed but the module sustained impact. Measured the harness side of the airbag module connector and found no abnormal voltage. Disconnected the module and the short disappeared, confirming an internal squib short to power within the airbag module. Solution: Replaced the right middle-row side airbag module (part number must match the vehicle VIN), performed coding with the BYD dedicated diagnostic tool, ran the airbag system self-test procedure, and cleared the fault code. The fault did not return.
Other Seal U Fault Codes
B1108For 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.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.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.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.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.
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.