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B169F

In BYD new energy vehicles, DTC B169F indicates an ESP (Electronic Stability Program) control unit communication fault, not an SRS airbag fault (early documentation may contain classification errors) — Qin Plus

Safety System

In BYD new energy vehicles, DTC B169F indicates an ESP (Electronic Stability Program) control unit communication fault, not an SRS airbag fault (early documentation may contain classification errors).

This fault code indicates the powertrain CAN or chassis CAN bus fails to receive a valid data frame from the ESP control module (integrated into the vehicle stability system, typically located on the left side of the engine compartment or inside the left front wheel arch), or the received signal fails verification.

This disables the Electronic Stability Program, traction control, anti-lock braking system (ABS), and advanced driver assistance functions relying on ESP signals (such as adaptive cruise control and lane keeping).

Root causes include a physical-layer CAN bus communication interruption, abnormal terminating resistance, a control unit power supply/ground fault, or a software version mismatch.

The B169F fault code on the Qin Plus indicates an ESP (Electronic Stability Program) control unit communication fault, where the CAN bus cannot receive valid data from the stability system module. This disables traction control, ABS, and driver assistance features. Severity is medium. Common causes include water damage or corrosion at the ESP module connector, or CAN bus wiring faults. Visit an authorised dealer for repair. Typical repair cost data is available based on 4 recorded cases.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Poor connection, oxidation, or water ingress at the ESP control module wiring harness connector (the module mounting location exposes it to splashing muddy water and car wash water intrusion, causing pin corrosion).
  • 2CAN bus circuit fault (CAN-H or CAN-L short or open circuit, disrupted twisted-pair spacing, or terminating resistance deviating from the standard value of 60Ω)
  • 3Abnormal ESP control unit power supply or ground (blown fuse, poor relay contact, or loose ground point causing voltage drop)
  • 4Control unit internal hardware damage (overvoltage, short circuit, or electrostatic breakdown damages the CAN transceiver chip, interrupting communication)
  • 5Software version mismatch or flashing failure (interrupted OTA update, or ESP module software incompatible with VCU/BCM)
What To Do
  • 1
    Use BYD dedicated diagnostic tool VDS2000/VDS3000 to read the complete fault codes and freeze frame data. Check for accompanying related fault codes such as U010104 (lost communication with ESP) or U030198 (software version mismatch).
  • 2
    Check the power supply voltage (standard 12V±0.5V) and ground resistance (less than 1Ω) of the ESP control module (part number usually BYD-3636100 series) to confirm the power and ground circuits are normal.
  • 3
    Measure CAN bus physical layer parameters: CAN-H to ground voltage 2.5-2.7V, CAN-L to ground voltage 2.3-2.5V, and differential voltage approximately 0.2V. Disconnect power and measure terminal resistance; the value should be 55-65Ω (if abnormal, check the 120Ω terminal resistor for damage or the wiring for a short circuit).
  • 4
    Check the ESP module wiring harness connector for proper sealing (especially at the mounting location inside the left front wheel arch). Inspect for water stains, copper oxidation, or loose pins. Clean with precision electrical contact cleaner and apply conductive paste/waterproof silicone grease.
  • 5
    Inspect the CAN wiring harness routing for crushing, damage, or insulation damage caused by rubbing against metal body parts. Focus on accident repair areas and wiring harness retaining clips.
  • 6
    Perform software diagnosis: Check if the ESP control unit software version matches the vehicle configuration. Try reflashing the latest software version (verify the vehicle battery level is >50% and the diagnostic tool connection is stable).
  • 7
    If all the above checks are normal, replace the ESP control module assembly. After replacement, perform the steering angle sensor calibration (steering wheel centering and left/right limit position learning), wheel speed sensor signal check, and ESP system self-learning procedure.
Real-World Cases
BYD DTC AI Analysis

Song Pro DM: Intermittent ESP warning while driving

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Symptoms: The ESP, ABS and tyre pressure warning lights suddenly illuminated on the dash while driving, displaying 'Check ESP System'. The fault occasionally cleared after cycling the ignition, but returned during subsequent driving. Diagnosis: VDS retrieved DTCs B169F (Lost Communication with ESP) and U010104. ESP module power supply and earth: normal. CAN line voltage: normal. Intermittent contact at pin 14 (CAN-H) of the module connector; fault reproduced when wiggling the wiring harness. Resolution: Replaced the ESP control module connector assembly (BYD-3636100). Re-crimped the pins and applied conductive grease. Measured termination resistance at 60Ω – normal. Road test confirmed the fault was resolved.
Original source ↗
BYD DTC AI Analysis

Qin Plus DM-i multiple system warnings on cold start

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Symptoms: During cold starts in winter, the engine, ESP, ABS and airbag lights illuminate simultaneously and may extinguish on their own after 5–10 minutes of driving. Frequency increases after rain or washing the vehicle. Diagnosis: Scanned DTCs B169F (ESP communication fault) and B1600 (airbag control unit communication fault, intermittent). Inspection revealed the ESP module, located above the left front wheel, is prone to water ingress. Disassembled the connector and found internal water staining and green copper corrosion. CAN line resistance fluctuated between 55–75 Ω. Resolution: Cleaned and blow-dried the connector, replaced the deteriorated seal (BYD-3636980), applied waterproof silicone grease and re-wrapped the wiring harness. Advised against high-pressure washing of the engine bay.
Original source ↗
BYD DTC AI Analysis

Tang DM: No communication with ESP after accident repair

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Symptoms: After the front collision repair, the vehicle displayed 'ESP malfunction' on startup and the steering was heavy (EPS relies on the ESP steering angle signal). Diagnosis: We scanned with VDS and retrieved codes B169F (invalid ESP signal) and C0035 (left front wheel speed sensor fault, historic). Inspection found a mounting screw had pinched the ESP module wiring harness during the accident repair, damaging the CAN wire insulation and shorting it to ground. Measured CAN-H resistance to ground: 0Ω. Fix: We repaired the damaged CAN wiring harness by insulating with heat-shrink tubing, rerouted the harness, replaced the possibly damaged ESP control module (BYD-3636100-B1), then performed steering angle sensor calibration and wheel speed signal checks after installation.
Original source ↗
BYD DTC AI Analysis

Han EV ESP communication error after OTA update

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Symptoms: After OTA update from V1.2 to V1.3, at startup the next day the ESP warning light stayed on. Adaptive cruise control and lane keeping assist did not work. Diagnosis: VDS read DTCs B169F (Lost Communication With ESP) and U030198 (Software Version Mismatch). The ESP module had software V2.1 but the VCU expected V2.2, suggesting an incomplete OTA flash. A re-flash attempt prompted ‘Communication Timeout’. Solution: Disconnected the battery negative terminal for 5 minutes to reset the CAN network. Used VDS offline mode to force-flash the ESP software to V2.2.1, keeping battery charge above 50%. Cleared fault codes afterward, then performed ESP system self-learning and EPB function check. Intelligent driving assistance functions returned to normal.
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.