AU
U1332

DTC U1332 indicates the airbag control unit (SRS ECU) receives an abnormal or interrupted vehicle speed signal via the CAN bus — Seal 6 EV

Safety System

DTC U1332 indicates the airbag control unit (SRS ECU) receives an abnormal or interrupted vehicle speed signal via the CAN bus.

In BYD new energy vehicles, the ESP electronic stability system (or IPB intelligent integrated braking system) typically generates the vehicle speed signal and transmits it to the SRS module via the chassis CAN or powertrain CAN bus.

The SRS system relies on the vehicle speed signal for crash algorithm decisions: at low speeds, it may trigger only the seat belt pretensioners without deploying the airbags, while at high speeds, it requires multi-stage airbag coordination.

CAN bus communication interruptions, signal source module failures, or SRS module receiving circuit faults trigger this code.

This fault causes the airbag system to enter a degraded mode, which may prevent correct deployment during a collision or cause the warning lamp to remain illuminated.

5
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1ESP/ESC control unit (or IPB intelligent integrated braking system) fault, preventing the generation or transmission of the vehicle speed signal.
  • 2Open circuit, short circuit, or excessive contact resistance in the CAN-H or CAN-L line between the SRS control unit and the gateway/ESP
  • 3Gateway module (GW) fault prevents vehicle speed signal forwarding across network segments.
  • 4Damaged internal CAN transceiver circuit in the SRS control unit or software fault.
  • 5Low 12V battery voltage or poor connection in the SRS system power supply/ground circuit causing abnormal CAN communication.
What To Do
  • 1
    Use VDS2000 or a dedicated BYD diagnostic tool to read fault codes. Determine if U1332 is a current or historical fault, and check for accompanying U-class communication fault codes (e.g., U1100 series).
  • 2
    Check the vehicle 12V battery voltage and SRS system fuses (usually located in the dashboard fuse box, e.g., F1/11, F2/16). Verify the power supply voltage is normal (12-14V).
  • 3
    Measure the resistance between pin 6 (CAN-H) and pin 14 (CAN-L) of the diagnostic connector (OBD). The standard value is approximately 60 Ω (two 120 Ω terminating resistors in parallel). If the resistance is abnormal (0 Ω, 120 Ω, or infinity), troubleshoot the CAN bus wiring.
  • 4
    Check the CAN harness connectors for the ESP/IPB module, gateway module, and SRS module. Specifically inspect the area under the dashboard and the floor harness pass-through for water ingress, corrosion, or backed-out pins.
  • 5
    Access the data stream function. Verify the ESP/IPB module outputs a normal vehicle speed signal and check the vehicle speed value the SRS module receives. If the ESP side is normal but the SRS side is abnormal, the fault is in the transmission path.
  • 6
    Disconnect the SRS module connector. Measure the CAN line-to-ground voltage (CAN-H approximately 2.6-2.7V, CAN-L approximately 2.3-2.4V) and wiring harness continuity. If the voltage is abnormal, check the gateway module or wiring harness.
  • 7
    If the wiring is normal, perform a power reset on the SRS module (disconnect the negative battery terminal for more than 5 minutes) or update the software. If the fault persists, replace the SRS control unit.
Real-World Cases
BYD DTC AI Analysis

Tang DM-i intermittent CAN vehicle speed signal loss

✓
2021 Tang DM-i intermittently displayed 'Check SRS System' while driving, with DTC U1332 intermittent. Found the floor wiring harness retaining clip below the left A-pillar loose; harness rubbed against the metal body edge and damaged the CAN-L wire insulation. Repaired and resecured the harness. Fault resolved. Front seat movement stresses the harness at this location.
BYD DTC AI Analysis

Faulty ESP module caused vehicle speed signal interruption in Yuan EV

✓
A 2019 BYD Yuan EV came in with DTC U1332 and the ABS warning light on. Diagnostics found an internal fault in the ESP module (Bosch 9.3) that stopped it sending vehicle speed frames to the CAN bus (ID:0x217). Replaced the ESP control unit and recalibrated; the SRS system then resumed normal communication. This case shows that vehicle speed signal source faults trigger cascading SRS faults.
BYD DTC AI Analysis

Song MAX Gateway Module Software Fault

✓
2019 Song MAX threw U1332 after collision repairs with the SRS light constantly on. Found the gateway module damaged in the crash—hairline cracks in the internal PCB were interrupting vehicle speed signal forwarding between powertrain and chassis CAN intermittently. Software update didn't fix it; replaced the gateway module and cleared the fault. Note: On accident-damaged vehicles, check the gateway mounting bracket for deformation.
BYD DTC AI Analysis

E1 EV wiring harness connector water ingress

✓
2020 BYD E1 threw code U1332 during the wet season; the undercarriage had been through water. Inspection found the GJK01 wiring harness connector for the SRS module beneath the floor had a perished seal that let water in, intermittently shorting CAN-H to the power supply. Cleaned the moisture, replaced the seal and connector terminals, cleared the fault. EVs need proper waterproofing on both high- and low-voltage harnesses.
BYD DTC AI Analysis

Qin Fuel SRS Module Internal Fault

✓
2020 BYD Qin (petrol) logged U1332 at 80,000 km with no other codes. CAN bus waveform normal; ESP vehicle speed signal output normal, but SRS module data stream showed 0 km/h. Internal CAN transceiver in SRS control unit faulty. Replaced SRS module and performed online configuration and coding. Recommend crash sensor calibration after replacement.
Other Seal 6 EV 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.