AU
U1332

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

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 U
  • 1ESP/ESC control unit (or IPB Intelligent Integrated Braking System) fault preventing vehicle speed signal generation or transmission.
  • 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 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 whether U1332 is a current or historical fault, and check for accompanying U-series communication fault codes (such as the U1100 series).
  • 2
    Check the vehicle 12V battery voltage and the SRS system fuse (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 infinity), check the CAN bus wiring.
  • 4
    Inspect the CAN harness connectors for the ESP/IPB module, gateway module, and SRS module. Specifically check under the dashboard and at the floor harness pass-throughs for water ingress, corrosion, or pin back-out.
  • 5
    Access the data stream function. Verify the ESP/IPB module vehicle speed signal output is normal. 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 and measure the CAN line voltage to ground (CAN-H approx. 2.6-2.7V, CAN-L approx. 2.3-2.4V) and harness continuity. If 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 U Fault Codes
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.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.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.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.