AU
B1751-00

B1751-00 is a Supplemental Restraint System (SRS) hard fault code indicating a short circuit to body ground (GND) in the right rear seat side airbag squib circuit (typically integrated into the seat backrest or C-pillar trim) — Atto 3

Safety System

B1751-00 is a Supplemental Restraint System (SRS) hard fault code indicating a short circuit to body ground (GND) in the right rear seat side airbag squib circuit (typically integrated into the seat backrest or C-pillar trim).

The SRS ECU internal detection circuit continuously monitors the airbag squib circuit resistance (normal range: 2.0-3.0 Ω; 1.6-2.1 Ω on some models).

The ECU registers a short to ground when it detects circuit resistance to ground below 1.0 Ω (near 0 Ω).

This fault causes the following: 1) The affected airbag fails to deploy during a collision, losing its protective function. 2) The SRS enters fail-safe mode, which may restrict seat belt pretensioner operation. 3) The instrument panel airbag warning light remains illuminated, indicating a critical safety hazard.

This is a level 3 severe fault requiring immediate repair.

The B1751-00 fault code on the Atto 3 indicates a severe SRS fault: a short to body ground in the right rear seat side airbag squib circuit. This can stop the airbag from deploying and may affect other restraint functions, so the vehicle should be inspected immediately. Common causes include damaged under-seat wiring from seat movement or an internal short in the airbag module. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Mechanical wear of the under-seat wiring harness: Frequent forward/backward movement or folding of the right rear seat causes long-term friction between the seat frame and the wiring harness sheath. Damaged insulation allows the wire to contact the metal vehicle body frame directly, creating a short to ground (most common cause, approx. 60% of cases).
  • 2Airbag module internal short circuit: The bridge wire inside the airbag inflator shorts to the housing. Airbag module aging, moisture ingress (water entering through open windows), or improper previous repairs typically cause this fault (approx. 25% of cases).
  • 3Connector corrosion or water ingress: Poor sealing at the wiring harness connector under the right rear seat (usually marked KJ10 or similar) allows water ingress after washing the vehicle or wading, causing a short circuit between terminals or to ground (approx. 10% of cases).
  • 4Improperly secured wiring harness: After accident repairs or interior trim removal and installation, failing to secure the wiring harness in the harness clips allows the seat slide rail to pinch or chafe the harness, resulting in a short to ground.
  • 5Internal SRS ECU fault: Damaged internal ECU detection circuit or driver chip triggers a false short-circuit fault (very rare; confirm only after ruling out other possibilities).
What To Do
  • 1
    Safety preparation: Set the vehicle power mode to OFF, disconnect the negative battery cable, and wait at least 90 seconds to fully discharge the SRS backup power supply and prevent accidental airbag deployment during repair.
  • 2
    Fault confirmation: Connect a genuine BYD diagnostic tool (such as VDS or ED400). Read the fault codes to confirm B1751-00 is present. Record the freeze frame data (ambient temperature and voltage). Attempt to clear the fault code, cycle the power, and observe if the fault returns.
  • 3
    Visual inspection: Remove the right rear seat (usually by loosening the seat retaining bolts and sliding backward). Inspect the yellow SRS wiring harness and connector (KJ10) under the seat for obvious wear, damaged insulation, water ingress, or an unlocked connector.
  • 4
    Circuit isolation test: Disconnect the right rear seat side airbag connector. Use a multimeter to measure the resistance between the harness-side terminals (B/Y black-yellow wire and Y/L yellow-green wire) and body ground. The normal value is greater than 1 MΩ (infinite). A lower resistance confirms a harness short to ground.
  • 5
    Voltage check: Keep the connector disconnected, switch the power mode to ON, and measure the voltage between the harness-side terminal and ground. Normal voltage is less than 1V. Any voltage reading indicates a possible internal ECU fault or a short circuit to another power wire.
  • 6
    Airbag module test: If wiring harness measurements are normal, connect a dedicated 2.0-3.0Ω resistor (or a known-good airbag simulator) across the wiring harness connector, then power on the vehicle. If the fault code clears and the SRS warning lamp turns off, this indicates an internal short circuit in the airbag module; replace the module.
  • 7
    Fault repair: If the wiring harness is damaged, wrap the damaged area with insulating tape, install corrugated conduit for protection, and re-secure the wiring harness away from the seat slide rail. If water enters the connector, clean it with electronic cleaner and blow dry; replace the connector if necessary. If the airbag module is faulty, replace it with a genuine airbag module (match the part number).
  • 8
    System reset: After completing the repair, reconnect all connectors and verify they are locked, install the seat, and connect the battery. Use the diagnostic tool to clear the fault code and perform the SRS system self-check (power on the vehicle, wait 10-20 seconds, and verify the SRS light turns off). Finally, perform a road test to verify the repair.
Real-World Cases
BYD DTC AI Analysis

Wiring harness chafing caused a short to ground.

✓
Symptoms: BYD Qin EV450 SRS warning light stays on. Scan tool reads DTC B1751-00. Diagnosis: Removed the right rear seat. Found the wiring harness protective sleeve beneath the seat rail damaged. Yellow-green wire insulation worn through, contacting the seat frame and causing a short to earth. Measured resistance to earth: 0.3Ω. Resolution: Taped the damaged section with electrical insulating tape. Fitted flame-retardant corrugated tubing. Rerouted the harness and secured it with cable ties to the seat base mounting slots, keeping clear of moving parts. Cleared the DTC. SRS light went out and function restored.
Original source ↗
BYD DTC AI Analysis

Internal short circuit in the airbag module

✓
Symptoms: After the vehicle drove through water (water entered because the right rear window was not fully closed), the SRS warning light illuminated, showing DTC B1751-00. Diagnosis: Disconnected the rear seat airbag connector and measured harness resistance to earth at >10MΩ (normal) and voltage to earth at 0V (normal), ruling out a harness fault. Bridged the circuit with a 2.5Ω resistor and the fault disappeared. Fitted the faulty airbag module to a known-good vehicle and the fault recurred, confirming an internal igniter short to earth within the airbag module. Resolution: Replaced the right rear side airbag module (part number must match the VIN). After fitting, performed system configuration and self-test. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Poor connector contact causing intermittent short circuit.

✓
Symptoms: SRS warning light illuminates intermittently, mainly on rough roads. Scan tool detected intermittent fault code B1751-00. Diagnosis: Inspection of the connector under the right rear seat found the locking tab not fully engaged, the connector loose, and minor oxidation on the internal terminals. On bumpy roads, vibration caused the terminals to contact the body, producing a momentary short circuit. Resolution: Cleaned the connector terminals with electrical contact cleaner and applied a small amount of conductive grease. Reconnected the connector firmly and made sure the locking tab engaged fully. Secured the connector with cable ties to prevent loosening. Completed a 20 km road test with no fault recurrence.
Original source ↗
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.