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B1736

DTC B1736 indicates the Supplemental Restraint System (SRS) detects a short to body ground in the igniter circuit of the right second-row seat side airbag (Side Airbag Module, located on the side of the right second-row seat) — Seal U

Safety System

DTC B1736 indicates the Supplemental Restraint System (SRS) detects a short to body ground in the igniter circuit of the right second-row seat side airbag (Side Airbag Module, located on the side of the right second-row seat).

Under BYD DTC coding rules, B1736 serves as the general identifier for this fault type.

A specific short to ground typically corresponds to B173611 (hexadecimal 11 indicates a short to ground).

This fault means the resistance between the two airbag igniter terminals, or between a terminal and the vehicle body, drops abnormally low (typically below 1.0 Ω).

The SRS ECU determines this is a short circuit.

This fault causes the airbag warning lamp to remain illuminated.

The system automatically cuts off the affected airbag circuit to prevent accidental deployment.

In a collision, the airbag may fail to deploy normally, severely compromising occupant safety.

Applicable models primarily include the Tang, Song MAX, and other 6-seat or 7-seat vehicles equipped with second-row side airbags.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Wiring harness wear at the seat slide rail: Frequent fore-and-aft adjustment of the right middle-row seat causes the lower yellow airbag wiring harness (usually located on the inner side of the seat rail) to rub against the metal bracket. Damaged insulation causes the copper wire to short to body ground.
  • 2Connector water ingress and oxidation: When driving through water or cleaning the interior, poor sealing of the under-seat airbag connector (yellow waterproof connector) allows moisture to enter and cause a short circuit between terminals or to ground. This condition is especially common in humid southern regions.
  • 3Improper seat removal and installation: During repairs or the installation of floor mats or seat covers, pulling the wiring harness during seat removal causes the airbag connector to loosen, pins to bend and contact the vehicle body, or metal clips to pierce the wiring harness insulation.
  • 4Airbag module internal fault: Manufacturing defects or prolonged vibration caused an internal short circuit in the right middle-row side airbag assembly igniter squib. Measuring the module connector shows an abnormal resistance close to 0Ω (normal: 2.0-3.0Ω).
  • 5Wiring harness retaining clip failure: The original wiring harness retaining clip detaches, causing the harness to rub continuously against the metal edge of the seat frame during seat adjustment, eventually wearing through the insulation and shorting to ground.
What To Do
  • 1
    Safe power-down and wait: Turn off the ignition, disconnect the negative battery cable, and wait at least 3 minutes (or 5 minutes per the workshop manual) to fully discharge the built-in SRS ECU capacitor and prevent accidental airbag deployment.
  • 2
    Preliminary visual inspection: Move the right middle-row seat (second row, right side). Inspect the yellow corrugated wiring conduit under the seat, inside the seat rail, and on the side of the backrest for wear, cuts, or crush marks. Inspect the connector for looseness, water ingress, or green copper corrosion.
  • 3
    Harness continuity test: Disconnect the right middle-row side airbag connector (located under the seat or at the backrest connection). Use a multimeter set to resistance to measure the resistance between each of the two harness-side terminals and body ground. The normal reading is infinity (OL). If the reading is 0-5 Ω, locate the short to ground.
  • 4
    Airbag module test: After confirming the wiring harness is normal, measure the resistance between the two pins on the airbag module side. The normal range is 2.0 ± 0.3 Ω (refer to the vehicle repair manual for exact specifications). If the resistance is close to 0 Ω, the airbag module has an internal short circuit. Replace the entire side airbag assembly.
  • 5
    Harness repair and protection: If the wiring harness is damaged, open the corrugated conduit and repair the harness by wrapping it in multiple layers of waterproof insulating tape (such as 3M Scotch 2228). Re-secure the harness, maintaining a clearance of more than 20mm from the seat frame to prevent further abrasion.
  • 6
    System reset and verification: Reconnect all connectors and the battery. Use the diagnostic tool to clear the fault code. Perform the 'SRS system self-check' or 'configuration reset' (some models require coding matching after replacing the airbag). Confirm B1736 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

Song MAX: Right middle row side airbag wiring harness worn through at guide rail, causing short circuit

✓
Vehicle: 2020 BYD Song MAX DM (6-seater) Symptom: Dashboard airbag warning light stayed on constantly. Diagnostic scan retrieved DTCs B1736/B173611. Repair: Found the yellow wiring harness beneath the right-hand middle-row seat pinched at the front of the seat slide rail. Repeated seat adjustments had worn through the insulation, leaving the bare copper wires touching the metal rail directly. Repaired the two damaged wires, wrapped them with double-layer waterproof insulation tape, rerouted the harness, and fitted abrasion-resistant corrugated tubing. Ensured the harness had enough slack to avoid future interference with the slide rail. Resolution: Fault cleared.
BYD DTC AI Analysis

Tang DM: Right middle-row side airbag connector shorted due to water ingress after wading

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Vehicle: 2021 Tang DM (7-seater). Symptom: After heavy rain, vehicle drove through floodwater; next day, airbag warning light illuminated on startup, logging DTC B1736. Repair: Found visible water droplets inside the airbag plug beneath the right-hand second-row seat (yellow 2-pin plug). Terminals were oxidised and blackened. Measured resistance between plug terminals and ground: 0.3 Ω. After removing water from the plug, cleaned terminals with electrical contact cleaner, applied conductive grease, and replaced the waterproof seal. Fault resolved. Recommendation: Check connector sealing on vehicles from the same production batch.
BYD DTC AI Analysis

Replaced right centre row side airbag module on BYD Yuan EV due to internal short circuit

✓
Vehicle: 2019 Yuan EV535. Issue: No accident history, but the airbag warning light suddenly illuminated with DTC B1736. Repair: Disconnected the airbag connector beneath the seat and measured the harness-side resistance to ground — normal (infinite). Measured the resistance between the two terminals of the airbag module (seat side airbag assembly) connector: 0.8 Ω (spec: 2.0 Ω), indicating an internal igniter short circuit. Replaced the right middle-row side airbag module (part number: ...), performed SRS system configuration write, and cleared the fault. Analysis of the old part found the internal igniter filament had fractured and shorted to ground due to a material defect.
BYD DTC AI Analysis

Rear seat removal and refitting on a Qin Pro caused the wiring harness clip to detach, resulting in a short circuit.

✓
Vehicle: 2020 Qin Pro Super Edition. Symptom: After the customer fitted full-surround seat covers, the airbag warning light came on with DTC B1736. Diagnosis: Inspection found the original harness retaining clip on the right middle-row seat had snapped during removal/refitting, letting the airbag harness hang and chafe against the seat height adjustment linkage. The damaged insulation caused a short to earth. Repair: Repaired damaged wiring and resecured the harness to the seat frame mounting holes with cable ties, preventing interference with moving parts.
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.