AU
B1654-00

DTC B1654-00 indicates a communication interruption or abnormal signal between the airbag control unit (SRS ECU) and the left front impact sensor — Atto 3

Safety System

DTC B1654-00 indicates a communication interruption or abnormal signal between the airbag control unit (SRS ECU) and the left front impact sensor.

This sensor typically mounts inside the left front fender or on the longitudinal beam.

It uses a two-wire communication circuit (signal wire and ground wire) and contains a piezoelectric or MEMS accelerometer with a normal resistance of approximately 2-3 kΩ.

The ECU sets this DTC if it cannot detect the sensor feedback signal during a self-test or drive cycle, if the resistance falls outside the calibrated range (open or short circuit), or if communication verification fails.

This fault disables the left front collision detection zone.

During a collision, it may prevent accurate airbag deployment or cause unintended deployment, making it a safety-critical fault.

4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Loose connector, backed-out pins, or oxidation: Sensor plug latch failure, terminal corrosion, or water ingress causes excessive contact resistance. This is the most common cause of intermittent faults.
  • 2Harness open circuit or damage: Sharp sheet metal edges cut the harness after left front fender repairs or collisions, or vibration breaks the wire during long-term use.
  • 3Internal sensor fault: Piezoelectric element aging, or moisture causing an internal circuit short or open, preventing the sensor from generating a correct acceleration signal.
  • 4Mounting bracket deformation: Incorrect sensor bracket alignment after accident repairs causes sensor mounting angle deviation or poor connector contact.
  • 5SRS ECU terminal fault: Poor contact or enlarged pin holes at ECU-side G36 connector terminals 33/34 (Qin model as an example) cause abnormal signal acquisition.
What To Do
  • 1
    Safety preparation: Power down the vehicle, disconnect the battery negative terminal, and wait at least 90 seconds to prevent accidental airbag deployment.
  • 2
    Fault confirmation: Connect the BYD dedicated diagnostic tool (such as X-431 or ED400), read and record DTCs, and confirm B1654-00 is a current fault, not a history fault.
  • 3
    Visual inspection: Verify the left front crash sensor connector (located near the left front fender liner or headlamp bracket) is fully seated. Inspect for obvious damage or signs of water ingress.
  • 4
    Circuit continuity test: Disconnect the ECU and sensor connectors. Measure the resistance between ECU terminal G36-33 and sensor terminal C35-2 (L/W wire), and between G36-34 and C35-1 (Br/W wire). Resistance must be less than 1 Ω. If resistance is infinite, trace the wiring harness to locate the open circuit.
  • 5
    Insulation test: Measure the resistance between the above wiring harness and body ground. The resistance must be greater than 10 MΩ to rule out a short to ground fault.
  • 6
    Sensor body inspection: Measure the resistance between the two sensor terminals. Normal resistance is 2-3 kΩ (refer to the vehicle repair manual for specific values). If out of range, replace the sensor.
  • 7
    Installation check: Verify the sensor mounting bracket is free of deformation, the sensor fits tightly against the bracket, and the arrow points in the required direction (typically toward the front of the vehicle).
  • 8
    Replacement verification: If the above checks are normal, swap the left-front and right-front sensors. Observe if the fault code transfers to confirm an internal sensor fault.
  • 9
    Repair and replacement: Repair harness damage (soldering + heat-shrink tubing), replace damaged sensors or connectors, and use genuine parts.
  • 10
    System reset: Reconnect all components, turn on the power, and clear the fault code using the diagnostic tool. Perform the SRS system self-check (with the ignition switch ON, the indicator light should turn off). Finally, perform a road test to verify the repair.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Poor connection at BYD S6 left front impact sensor connector

✓
The SRS warning light on the instrument cluster illuminated intermittently. The scan tool retrieved DTC B1654-00. Inspection found the locking tab of the collision sensor connector inside the left front fender was loose, with minor oxidation on the terminals. Wiring harness continuity and sensor resistance tested normal. Repair: cleaned the terminals with electronic cleaner, repaired the locking tab, applied conductive grease and reconnected the connector. Cleared the fault code; issue resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin: wiring harness open circuit after accident repair

✓
After left front accident repair, the SRS light stayed on with DTC B1654-00. The sensor connector was good, but the L/W wire (G36-33 to C35-2) had infinite resistance between ECU and sensor. Disassembly found the harness at the inner fender liner cut through by a sharp sheet metal edge. Repair: Cut open the harness sheath, soldered the broken wire, insulated with double-layer heat shrink tubing, rerouted the harness away from sharp edges, and replaced the damaged sensor. Fault cleared.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Surui: Missed connector during accident repair

✓
After front bumper collision repair, the dashboard displayed an airbag warning. Read DTC B1654-00. Inspection found the left front crash sensor connector completely unplugged (the mechanic forgot to connect it). Reconnected the plug and cleared the code. After driving for a while, the fault returned. Further inspection revealed the sensor mounting bracket was deformed in the accident, preventing the sensor from seating properly and putting the connector under tension, causing poor contact. Repair: corrected the bracket flatness, replaced the sensor with a new one, ensured the connector lock clicked fully into place, and secured the wiring harness clip.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal piezoelectric element failure in BYD S6 sensor

✓
Vehicle had no collision history. The SRS warning light suddenly illuminated and DTC B1654-00 would not clear. Wiring harness continuity was normal; connectors showed no abnormalities; supply voltage measured 12V (normal). Swapped the left and right front sensors — the fault code changed to B165D-00 (right front sensor fault), confirming an internal failure of the original left front sensor. Disassembly revealed the internal piezoelectric ceramic plate had desoldered. Replaced the OEM left front impact sensor, cleared fault codes, and performed static and dynamic road tests. System returned to normal.
Original source ↗
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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]