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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) — Qin Plus

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.

3
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Mechanical wear of the under-seat wiring harness: Frequent fore/aft movement or folding of the right rear seat causes long-term friction between the seat frame and the wiring harness sleeve. This friction damages the insulation layer, allowing the wire to directly contact the vehicle's metal frame and create a short to ground (most common cause, accounting for approximately 60% of cases).
  • 2Airbag module internal short circuit: The airbag igniter internal bridge wire shorts to the housing. Common causes include airbag module aging, moisture (water ingress from open windows), or improper previous repairs (approximately 25% of cases).
  • 3Connector corrosion or water ingress: The wiring harness connector under the right rear seat (usually marked KJ10 or similar) seals poorly. Water enters after car washes or wading, causing terminal-to-terminal or terminal-to-ground short circuits (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 retaining clips allows the seat slide rail to pinch or chafe the harness, causing a short to ground.
  • 5Internal SRS ECU fault: A damaged internal detection circuit or driver chip triggers a false short-circuit fault (very rare; rule out other possible causes before confirming).
What To Do
  • 1
    Safety preparation: Turn the vehicle power switch to OFF and disconnect the negative battery cable. 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, power on again, and observe if the fault recurs.
  • 3
    Visual inspection: Remove the right rear seat (usually requires loosening the seat retaining bolts and sliding the seat backward). Inspect the yellow SRS wiring harness and connector (KJ10) under the seat for obvious wear, damaged insulation, signs of 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. Normal resistance is greater than 1MΩ (infinite). If the resistance is too low, the harness is shorted to ground.
  • 5
    Voltage check: Keep the connector disconnected and set the power mode to ON. Measure the voltage between the harness-side terminal and ground. Voltage should be less than 1V. If voltage is present, suspect an internal ECU fault or a short circuit to another power wire.
  • 6
    Airbag module test: If wiring harness measurements are normal, bridge the wiring harness connector using a dedicated 2.0-3.0Ω resistor (or a known-good airbag simulator) and power on again. If the fault code clears and the SRS warning lamp turns off, the airbag module has an internal short circuit. Replace the airbag 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 harness away from the seat slide rail. If water entered the connector, clean with electrical contact cleaner, blow dry, and replace the connector if necessary. If the airbag module is faulty, replace with a genuine airbag module (verify part number match).
  • 8
    System reset: After completing the repair, reconnect and lock all connectors. Install the seat. Connect the battery. Use the diagnostic tool to clear the fault code. Perform an SRS system self-check (power on the vehicle, wait 10-20 seconds, and verify the SRS warning 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 Qin Plus 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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.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.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus 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.