AU
B169700

This DTC has two definitions across different BYD vehicle platforms: 1) In early models such as the E2, E3, and Qin EV, it indicates an internal fault in the SRS_ECU (airbag control unit) involving communication, power supply, or internal circuit failures in the main safety system control module, potentially affecting crash protection functions — Qin Plus

Safety System

This DTC has two definitions across different BYD vehicle platforms: 1) In early models such as the E2, E3, and Qin EV, it indicates an internal fault in the SRS_ECU (airbag control unit) involving communication, power supply, or internal circuit failures in the main safety system control module, potentially affecting crash protection functions. 2) In models equipped with seat memory such as the Song MAX, Song Pro, Tang, and Song PLUS, repair databases indicate this DTC usually flags a Driver Seat Position Memory - Store 1 Malfunction.

This involves Seat Control Module (SCM) storage or recall failures for memory position 1, or distorted signals from related position sensors (fore-aft/height/tilt).

In either case, the control module detects abnormal internal storage, a communication timeout, or actuator feedback signals exceeding the threshold.

Confirm the fault subtype using the VDS diagnostic tool based on the specific vehicle model.

5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Abnormal power supply or ground to the Seat Control Module (SCM) or SRS ECU, specifically a voltage drop or momentary power loss in the IG1 power supply under specific operating conditions.
  • 2Abnormal seat position sensor (fore-aft position, height adjustment, backrest recline) signal, damaged sensor, or sensor wiring harness short or open circuit due to pinching or chafing during seat rail movement.
  • 3Wiring harness connector under the seat (such as the M1 connector) oxidized or loose, or terminal backed out, causing excessive contact resistance.
  • 4Dry solder joint on the seat control module's internal memory chip, corrupted EEPROM data, or module software version mismatch with the vehicle control unit (common after an OTA update)
  • 5Insufficient low-voltage battery voltage (<12V) or DC-DC converter output fluctuation causes the control module to reset during high-current seat adjustment.
What To Do
  • 1
    Use the VDS2000 diagnostic tool to scan all vehicle systems. Verify the specific definition, freeze frame data, and environmental conditions of DTC B169700. Read the seat position sensor data stream (fore-aft, height, and backrest angle values) or the SRS system status.
  • 2
    Check the power supply circuits (constant power B+, ignition switch IG1) and ground points of the relevant control module (seat control module or SRS ECU). Verify the measured voltage is within 12V ± 0.5V. Check if fuse F2/14 (seat control) is blown.
  • 3
    Inspect the under-seat wiring harness connectors (especially M1 and M2) for oxidation or water ingress. Check if the seat frame pinches or chafes the wiring harness on the inner side of the seat rail when moving the seat to the fully forward or fully rearward position, causing insulation damage.
  • 4
    Check the seat position sensor installation status and signal output consistency. Compare the actual position with the data stream display value. If necessary, use an oscilloscope to check the sensor signal waveform.
  • 5
    Perform a control module power reset: disconnect the battery negative terminal for 15 minutes, or remove the seat control module/SRS ECU fuse for at least 10 minutes, then reinstall it. Clear the fault code, cycle the power, and test.
  • 6
    If the fault recurs, update the seat control module software to the latest version or replace the seat control module/SRS ECU assembly. After replacement, perform the complete seat position memory learning procedure or airbag system self-check configuration.
Real-World Cases
BYD DTC AI Analysis

BYD Song MAX driver seat memory function completely inoperative.

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Symptoms: When the vehicle was powered on, the driver seat memory function failed completely. Pressing M and buttons 1/2 gave no response; the seat could not save or recall preset positions. Power adjustment worked normally, and no warning lights appeared on the dash. Diagnosis: VDS2000 retrieved DTC B169700 (Driver Seat Position Memory Storage 1 Fault) from the left body domain controller. Live data showed normal position sensor signals but abnormal memory module internal storage. Checking the seat control module power supply revealed a voltage drop on IG1, and the M1 connector beneath the seat had slight oxidation. Solution: Cleaned and re-tightened the M1 connector harness, performed a power reset on the left body domain controller (disconnected the battery negative terminal for 15 minutes), and ran the seat position memory learning procedure with VDS to recalibrate the sensors. Fault cleared.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro DM seat position fails to save and intermittently resets

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Symptoms: While driving, the dashboard intermittently displayed a "Check Seat System" warning. The driver's seat lost its saved memory positions after switching the ignition off and back on. Occasionally, when entering the vehicle, the seat would automatically move to the fully forward or rearward position instead of the preset position. Diagnosis: VDS scan revealed the seat control module had logged DTCs B169700 (Driver Seat Position Memory - Memory 1 Fault) and B169800 (Memory 2 Fault). Data stream analysis showed intermittent fluctuations in the horizontal position sensor signal. Upon removing the seat, we found the position sensor wiring harness inside the seat rails was pinched and worn. We also measured low battery voltage (11.8V) and detected fluctuating DC-DC output. Solution: Repaired the damaged wiring harness inside the seat rails and rerouted it to prevent interference. Replaced the faulty DC-DC converter assembly. Replaced the seat horizontal position sensor. Reflashed the seat control module software to the latest version. Reset and saved the seat memory positions.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM seat memory malfunction and incorrect positioning

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**Symptoms:** Driver seat memory function malfunction. Pressing memory button 1 moves the seat to an incorrect position; sometimes the memory function fails completely, though manual seat adjustment works normally. The fault occurs intermittently after the vehicle has been parked for a period. **Diagnosis:** VDS scan retrieved DTC B169700 (Driver Seat Position Memory Switch - Memory 1 Malfunction). The seat memory switch resistance tested normal. Further inspection found intermittent CAN communication timeouts between the Seat Control Module and Left Body Domain Controller. Disassembly of the Seat Control Module revealed cold solder joints on the internal memory chip (a known issue affecting certain production batches). **Solution:** First reflashed the Seat Control Module software; the fault temporarily cleared but returned after one week. Replaced the driver seat control module assembly, then performed the complete seat position learning procedure. Advised the customer to avoid frequent plugging and unplugging of the charging cable to prevent voltage spikes.
Original source ↗
BYD DTC AI Analysis

BYD Song MAX power seat and memory function failed simultaneously.

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Symptoms: All electric adjustment functions for the driver's seat (fore-aft movement, backrest angle, height adjustment) failed suddenly without warning. The memory function also stopped working. Diagnosis: Checked the seat control fuse. F2/14 (seat control module fuse) was blown. Replaced it, but the new fuse blew immediately, indicating a short circuit. Disassembled the seat to inspect the wiring harness. Found the harness under the seat pinched when the seat was in its fully forward position; damaged insulation caused a short to ground. VDS scan showed fault code B169700 and seat motor-related fault codes. Resolution: Repaired the damaged harness, re-wrapped it, and rerouted it to prevent interference with the seat frame. Replaced the seat control fuse. Cleared fault codes and tested all seat and memory functions — returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Song Plus DM-i seat memory function limited after OTA update

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Symptoms: The instrument cluster shows a seat memory function limitation. The driver’s seat memory cannot save new positions, though previously stored positions recall normally. The fault appeared after a vehicle OTA update. Diagnosis: VDS scan found DTC B169700 (Driver Seat Position Memory - Memory 1 Fault) in the seat control module. Checking the seat control module version revealed a version mismatch with the new vehicle controller. Live data showed an abnormal write status flag for memory storage area 1. Solution: Reset power to the seat control module by disconnecting its connector or removing the fuse for over 10 minutes. Use the VDS to run the control module reset and learning procedure. Recalibrate the seat position sensors. If the fault persists, flash the seat control module to the latest software version. Fault resolved.
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.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.