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B1680-00

DTC B1680-00 indicates the SRS (Supplemental Restraint System) control module detected an open circuit in the Passenger Airbag Cutoff Switch or its related wiring — Seal U

Safety System

DTC B1680-00 indicates the SRS (Supplemental Restraint System) control module detected an open circuit in the Passenger Airbag Cutoff Switch or its related wiring.

This switch, typically located in the center console or glovebox area, manually disables the airbag when a child seat occupies the front passenger seat.

The fault occurs because the SRS ECU fails to detect a valid resistance signal from the switch during the self-check cycle (normally a specific resistance range, such as 2-5kΩ, or a ground signal), triggering a level-two safety warning.

This condition may forcibly disable the front passenger airbag or place it in an uncertain state, severely compromising the occupant protection strategy during a collision.

The fault also illuminates the SRS warning light on the instrument cluster and prevents the vehicle from passing a safety inspection.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Qin EV300 SRS light on after dashboard modification

✓
When the vehicle arrived, the instrument cluster displayed a constant airbag warning light. The customer reported the fault appeared after an external modification shop installed a centre infotainment screen. Using VDS, we read current fault code B1680-00. We found the passenger airbag switch wiring harness connector was not fully seated. During the retrofit, pulling when removing the dashboard caused the connector to loosen and the locking tab to break. We reconnected the connector and secured it with cable ties. After clearing the fault code, the SRS system returned to normal. We test drove the vehicle for 30 kilometres without the fault reoccurring.
BYD DTC AI Analysis

BYD Qin 100 passenger airbag switch failed after wading.

✓
A 2017 Qin 100's SRS warning light came on after driving through deep water during heavy rain. The scan tool showed codes B1680-00 and B167F-00 (passenger airbag circuit low resistance). Inspection found a poorly sealed wiring harness grommet on the passenger floor, allowing water to enter and corrode the switch connector pins. Disassembly revealed internal oxidation of the switch and green copper corrosion on the wiring terminals. Replaced the passenger airbag switch assembly, treated the corroded wiring sections, and re-sealed the waterproofing. Fault resolved. Recommend checking the vehicle's drain holes for blockages.
BYD DTC AI Analysis

Intermittent SRS fault on BYD Qin EV450

✓
The customer reported the SRS warning light occasionally illuminating, clearing after cycling the ignition. Scanned history DTCs and found multiple B1680-00 entries. Wiggling the passenger footwell wiring harness reproduced the fault. Close inspection revealed fretting wear on the switch connector pins, causing unstable contact resistance (normal <1Ω, faulty >10Ω). Replaced the wiring harness connector, adjusted pin tension, applied conductive grease to the contact surfaces, and conducted a continuous rough road test for 2 hours. The fault did not reappear; repair confirmed.
BYD DTC AI Analysis

Airbag control module false positive

✓
No accident history. SRS light suddenly illuminated, only DTC B1680-00 set. Measured switch and harness: both normal, resistance values meet workshop manual spec (3.2kΩ). Suspected internal sampling circuit fault in SRS ECU. Attempted software update (V1.2 to V1.4), fault persisted. Replaced SRS module with identical unit, performed coding. Fault code cleared and did not return. Testing found original ECU had damaged internal A/D converter chip.
BYD DTC AI Analysis

Passenger airbag switch internal mechanical sticking

✓
During routine servicing, found the SRS warning light on with fault code B1680-00. Inspection revealed the customer had left the passenger airbag disable switch (inside the glovebox) in the OFF position for an extended period and never toggled it. Disassembled the switch and found the contact points of the internal slider mechanism had oxidised and seized due to long-term inactivity, failing to produce a valid resistance signal. Cleaned and lubricated the internal switch contacts, demonstrated correct usage to the customer (advising periodic toggling to prevent oxidation), rectified the fault, and avoided unnecessary replacement.
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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.