AU
U1332

DTC U1332 indicates the airbag control unit (SRS ECU) receives an abnormal or interrupted vehicle speed signal via the CAN bus — Atto 8

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 — Atto 8
  • 1Fault in the ESP/ESC control unit (or IPB Intelligent Integrated Braking System) preventing vehicle speed signal generation or transmission.
  • 2Open circuit, short circuit, or high contact resistance in the CAN-H or CAN-L line between the SRS control unit and the gateway/ESP.
  • 3Gateway module (GW) fault causing vehicle speed signal forwarding failure across network segments.
  • 4Damaged internal CAN transceiver circuit in the SRS control unit or software fault.
  • 5Low 12V battery voltage or poor contact in the SRS system power supply/ground circuit, causing abnormal CAN communication.
What To Do
  • 1
    Use VDS2000 or a BYD dedicated diagnostic tool to read fault codes. Confirm if U1332 is a current or history 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 (typically 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 OBD diagnostic connector. The standard value is approximately 60 Ω (two 120 Ω terminating resistors in parallel). If the resistance is abnormal (0 Ω, 120 Ω, or infinite), check the CAN bus wiring.
  • 4
    Check the CAN harness connectors of the ESP/IPB module, gateway module, and SRS module. Inspect the area under the dashboard and the floor harness pass-through for water ingress, corrosion, or backed-out pins.
  • 5
    Enter the data stream function. Check if the ESP/IPB module outputs a normal vehicle speed signal, and simultaneously 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 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 at least 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 Atto 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.