AU
B165E-00

DTC B165E-00 indicates an abnormally low-impedance connection (short to ground) between the airbag system (SRS) right front impact sensor signal or power circuit and body ground (GND) — Seal U

Safety System

DTC B165E-00 indicates an abnormally low-impedance connection (short to ground) between the airbag system (SRS) right front impact sensor signal or power circuit and body ground (GND).

This sensor typically mounts on the right front side member, radiator support, or fender reinforcement to detect collision acceleration on the right front side of the vehicle.

A short to ground prevents the SRS control unit (ACU) from correctly reading the sensor's acceleration signal output (typically an analog or digital signal from a piezoelectric or MEMS sensor).

This causes the following conditions: 1) airbags failing to deploy during an actual collision; 2) the system entering fail-safe mode and illuminating the SRS warning lamp; 3) in extreme cases, abnormal signals causing unintended airbag deployment.

This safety-critical fault requires immediate repair.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Front bumper wiring harness wear: Vehicle vibration causes the right front crash sensor wiring harness to rub against the body metal frame (such as the side member or fender liner). This damages the insulation, exposes the wire, and causes a short to body ground. This commonly occurs on vehicles with improperly secured harnesses or missing clips following accident repairs.
  • 2Wading or water ingress corrosion: Driving the vehicle through water (water level above the wheel center) or high-pressure washing allows water to seep through the sensor connector seal or wiring harness corrugated conduit. This causes oxidation and electrolytic corrosion of the connector terminals, creating a short-to-ground path. This commonly occurs in older vehicles with poor sealing.
  • 3Improper modification or repair damage: When routing wiring for aftermarket LED headlights, front radar, or dash cams, technicians tie the aftermarket harness too tightly to the SRS harness with cable ties, or cut the original harness insulation when drilling holes for wires, exposing the conductor and causing a short circuit to the vehicle body.
  • 4Internal sensor circuit fault: Breakdown of the crash sensor internal integrated circuit (IC) or capacitor causes a short circuit between the power supply pin and the ground pin, or the internal pull-down resistor at the signal output terminal fails. Sensor aging, overvoltage, or electrostatic damage typically causes this.
  • 5SRS control unit (ACU) internal fault: In very rare cases, the ACU internal signal acquisition circuit for the right front sensor fails, incorrectly detecting a short to ground. Swap the left and right sensors to confirm.
What To Do
  • 1
    Safety preparation: Shift the vehicle into P/Neutral, apply the parking brake, turn off the ignition switch, and disconnect the negative battery cable. Wait at least 90 seconds to fully discharge the airbag system capacitor and prevent accidental airbag deployment during repair.
  • 2
    Fault confirmation: Connect the BYD dedicated diagnostic tool (VDS2000/3000). Enter the SRS system and read the fault codes. Confirm B165E-00 is a current fault (not a history fault). Record the freeze frame data (such as vehicle speed and time of occurrence). Attempt to clear the fault code and check if it reappears immediately.
  • 3
    Visual inspection: Remove the right front bumper or fender liner. Inspect the right front crash sensor (usually located at the front end of the right front longitudinal beam) for physical damage or cracks. Inspect the wiring harness connector for looseness, water ingress, corrosion, or bent pins. Inspect the wiring harness retaining clips for detachment.
  • 4
    Circuit measurement: Disconnect the sensor connector. Use a multimeter to measure the resistance to ground for each terminal on the harness-side connector. Signal wire resistance to ground should be >1MΩ (infinite). A reading of 0-5Ω confirms a short to ground. Measure the power wire resistance to ground; it should also be >1MΩ. Measure the resistance between the sensor body terminals and compare it with the repair manual standard value (usually 2-3kΩ).
  • 5
    Wiring harness inspection: If testing confirms a short circuit, carefully inspect the insulation along the right front wiring harness route (from the sensor to the SRS ECU, usually passing below the right A-pillar). Check metal edge contact points, pass-through grommets, and intersections with other harnesses for abrasion, cuts, or burn marks.
  • 6
    Fault repair: For damaged wiring harnesses, wrap with heat-shrink tubing or waterproof tape. Replace the entire wiring harness if necessary. For water ingress in connectors, clean with electrical contact cleaner, blow dry with an air gun, and apply conductive protective grease (such as Stabilant 22). Replace the connector or sensor if necessary. For internal sensor faults, replace with genuine parts (part number must match the VIN).
  • 7
    Verification test: Restore all connections, reinstall the bumper, and connect the battery. Turn the ignition switch to the ON position. Use the diagnostic tool to clear the fault code and perform the SRS system self-check (usually requires a drive cycle or specific operation). Verify DTC B165E-00 does not return and the instrument cluster SRS warning lamp turns off. Read the data stream to verify the right front sensor acceleration value is within the normal range (0±0.5G).
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD S6 right front impact sensor wiring harness chafed, causing a short to ground.

✓
Symptoms: The SRS warning light on the instrument panel remained illuminated. Scanned with a diagnostic tool and retrieved DTC B165E-00 (Right Frontal Impact Sensor Short to Ground). The vehicle had no collision history, but a repair shop had repainted the front bumper two weeks prior. Diagnosis: Connected VDS and confirmed the DTC was present and could not be cleared. Removed the front bumper and inspected the right front impact sensor; the sensor appeared undamaged but the connector was loose. Disconnected the sensor plug and measured 0.3Ω resistance to ground at the harness side (abnormal continuity). Traced the wiring route and found the harness inside the front bumper had chafed against the chassis rail edge due to missing retaining clips. The insulation was damaged at three points, exposing copper wire and causing contact with the body. Repair: Cut out the damaged harness section. Spliced with same-colour cable, soldered the joints, and applied double-layer heat-shrink insulation. Re-secured the harness routing with cable ties to maintain at least 20mm clearance from metal components, and fitted protective corrugated tubing. After reassembly, cleared the DTC. The SRS warning light extinguished and the data stream showed normal readings.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Water entered the sensor connector on the BYD Qin EV after driving through water, causing oxidation and a short circuit.

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Symptoms: The owner reported that after driving through a flooded section (water depth approximately 30 cm) in the rain, the SRS warning light stayed on. The vehicle drove normally but displayed 'Check Airbag System'. Retrieved DTC B165E-00 with a diagnostic tool. Diagnosis: Inspected the right front impact sensor mounting location and found the sensor positioned low (near the front subframe). Removed the sensor and found obvious water traces and green copper corrosion inside the connector. Measured sensor body resistance as normal (2.1 kΩ), but resistance between the connector terminal and sensor housing measured 1.2 Ω (abnormal continuity). Water entered the connector during wading, shorting the power terminal to the sensor metal housing (ground) through a water film. Resolution: Cleaned connector terminals and sensor pins with anhydrous alcohol. Thoroughly dried with a high-pressure air gun (do not use heat guns; high heat can damage seals). Applied BYD conductive protectant (Part No. BYD-393) and replaced the waterproof seal. Test drove and followed up after one week; the fault has not recurred.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Modified headlights caused SRS short-to-ground fault in BYD Song

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Symptom: After upgrading the LED headlights at an unauthorised modification workshop, the owner started the vehicle and the SRS warning light illuminated. The scanner read fault code B165E-00. The workshop had removed the front bumper and rerouted the wiring during the modification. Diagnosis: Checked the right front impact sensor connector and found it properly connected, but discovered the workshop had tightly bundled the LED headlight driver power cable (high current) with the SRS sensor harness using cable ties. Further inspection found a cut in the headlight power cable insulation, which made contact with the sensor signal wire. The technician had also loosened the sensor earth wire and failed to tighten it to the standard torque (8 Nm), causing increased contact resistance and intermittent short circuits to earth during vehicle vibration. Resolution: Completely separated the headlight wiring from the SRS harness, repaired the damaged power cable with insulation tape, and retightened the sensor earth bolt to the specified torque. Tidied the wiring route to ensure clearance from sharp metal edges. Cleared the fault code, conducted a road test and a rough road test; the fault did not recur.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD E1 sensor internal IC breakdown causing intermittent short to ground

✓
Symptoms: Intermittent SRS warning light. Light functioned normally during cold starts but came on after 10–15 minutes of driving. Scan tool read active DTC B165E-00. Diagnosis: Inspected wiring harness – no visible damage; measured harness ground resistance – normal. Used an oscilloscope to monitor the sensor signal waveform. When the fault appeared, the signal line dropped to ground potential. Swapped left and right front impact sensors; DTC changed to B165D-00 (left front sensor short circuit), confirming the fault followed the sensor. Disassembled the faulty sensor and found capacitor breakdown damage on the PCB. Determined an internal voltage regulation circuit failure caused a power-to-ground short. Solution: Replaced with a genuine right front impact sensor (BYD-3636100). Monitored the vehicle continuously for 3 days after replacement; fault completely eliminated.
BYD DTC AI AnalysisFrom Chinese market (translated)

Improperly secured wiring harness after accident repair caused a short circuit on the BYD Qin 100

✓
Symptoms: Minor right-front collision (speed <15 km/h). After the workshop replaced the right front wing and bumper, the SRS warning light came on. Retrieved DTC B165E-00. Diagnosis: Inspected the newly installed right front impact sensor (aftermarket part) – no visible damage, but measured a short to earth on the signal wire. Found that during the repair the workshop had not routed the harness to factory specification; instead, it was trapped between the wing reinforcement and the chassis rail. A sharp edge cut 3 wires in the harness, including the signal wire, which contacted the body metal and created a short to earth. Solution: Replaced the damaged harness section (from the sensor to the main harness branch point) using the factory wiring repair procedure (soldering and heat-shrink tubing). Rerouted the harness and secured it at the original clip positions, ensuring safe clearance from crumple zone metal components. Installed a genuine impact sensor. Fault resolved.
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. Sources: [1]