AU
U1332-00

DTC U1332-00 indicates the airbag control unit (SRS ECU) receives an abnormal or timed-out vehicle speed signal via the body CAN bus (B-CAN) — Atto 8

Safety System

DTC U1332-00 indicates the airbag control unit (SRS ECU) receives an abnormal or timed-out vehicle speed signal via the body CAN bus (B-CAN).

This fault occurs when the SRS module fails to receive a valid vehicle speed data frame from the instrument cluster or ABS/ESP module within the predetermined cycle, preventing the airbag system from determining collision severity based on real-time vehicle speed.

This safety system communication fault compromises the collision safety strategy, potentially causing airbag deployment timing deviations during high-speed collisions or false deployments during low-speed collisions.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Instrument cluster internal CAN communication module or gateway fault prevents transmission of the vehicle speed signal to the B-CAN network.
  • 2The internal CAN transceiver in the SRS control unit is damaged and cannot receive or decode vehicle speed data frames.
  • 3B-CAN network physical layer fault, including water ingress and oxidation at the G10/M40 connector, wiring harness damage causing short or open circuits, or excessive contact resistance.
  • 4Abnormal network termination resistance (standard value approximately 60Ω; the SRS and instrument cluster modules provide this in parallel), causing signal reflection or attenuation.
  • 5Using a non-genuine instrument cluster or SRS module during accident repairs causes a CAN communication protocol mismatch or incompatible software version.
What To Do
  • 1
    Use the dedicated diagnostic tool to read the fault code and record freeze frame data. Confirm the vehicle speed, time, and environmental conditions when the fault occurred.
  • 2
    Visually inspect the vehicle speed display on the instrument cluster to determine if the fault is a signal source issue (no display on the instrument cluster) or a data transmission issue (instrument cluster operates normally but the SRS reports a fault).
  • 3
    Measure the CAN bus voltage at the diagnostic port: CAN-H should be 2.5-2.7V and CAN-L should be 2.3-2.5V. Confirm the bus physical layer base voltage is normal.
  • 4
    Disconnect SRS module connector G10 and measure the terminating resistance between terminals G10-2 (B-CAN-L) and G10-3 (B-CAN-H). The standard value is approximately 60Ω (two 120Ω resistors in parallel). If the resistance is abnormal, inspect the wiring section by section.
  • 5
    Check the SRS module power supply (constant battery and ignition feeds) and ground circuits. Verify the voltage drop is less than 0.1V to rule out power supply interference causing communication interruption.
  • 6
    Use an oscilloscope to monitor the B-CAN waveform and check for missing data frames, bit errors, ACK errors, or signal distortion. Focus on the G10 connector and the wiring harness bend at the left A-pillar.
  • 7
    Check CAN wiring insulation. Measure CAN-H and CAN-L resistance to ground and power. Inspect for water ingress corrosion or wiring harness wear causing intermittent short circuits.
  • 8
    Verify by substitution: Replace the instrument cluster or SRS module with a component of the same model. Observe if the fault code transfers to confirm the faulty component.
  • 9
    After repairing the wiring or replacing the faulty module, clear the fault code and perform a road test to verify the SRS system receives the vehicle speed signal in real time and the fault light is off.
Real-World Cases
BYD DTC AI Analysis

BYD S6 instrument cluster CAN module damage caused loss of vehicle speed signal

✓
The airbag warning light illuminated on the instrument cluster. The scanner retrieved DTC U1332-00. The speedometer displayed normal readings while driving, but the SRS system reported a vehicle speed fault. The technician checked B-CAN network communication with an oscilloscope and found it normal, but found that speed data frames sent from the instrument cluster to the SRS were occasionally lost. The technician traced the fault to the internal CAN communication module in the instrument cluster and replaced the assembly with a genuine part. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD NEV precharge resistor failure caused CAN network failure

✓
The vehicle presented with a powertrain fault and multiple CAN communication DTCs including U1332-00. Diagnosis found a damaged front-end pre-charge resistor in the high-voltage battery pack, disrupting communication between the BMS and vehicle controller and affecting vehicle speed signal transmission across the CAN network. Replaced the pre-charge resistor and performed cell balancing on the battery pack. Network communication returned to normal and the U1332 DTC cleared.
Original source ↗
BYD DTC AI Analysis

Protocol mismatch caused by non-genuine instrument cluster in accident-repaired vehicle

✓
After accident repairs, the airbag warning light stayed on. Retrieved DTC U1332-00. Inspection found an aftermarket instrument cluster installed during the repair. The speedometer displayed correctly, but the cluster’s CAN protocol differed from the SRS module’s, so the SRS could not parse the vehicle speed data. Replaced the cluster with an OEM unit and reconfigured the SRS system parameters. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD S6 left A-pillar wiring harness damage causing intermittent CAN-L short circuit

✓
On starting the vehicle after parking, the airbag warning light illuminated with DTC U1332-00 stored. Inspection found water stains on the G10 connector. Further investigation revealed the wiring harness beneath the left A-pillar had insulation damage from a previous accident repair, contacting the body metal and causing an intermittent short to ground on the CAN-L line. Repaired the damaged wiring, cleaned oxidation from the connector and applied waterproofing. Fault cleared.
Original source ↗
BYD DTC AI Analysis

Internal transceiver damage in SRS control unit caused vehicle-wide communication failure

✓
Multiple warning lights (ABS, SRS, ESP) illuminated simultaneously while driving. Scanner retrieved communication fault codes including U1332-00 and U0140. Using segmented troubleshooting, disconnected the SRS module; other systems returned to normal. Confirmed faulty CAN transceiver inside the SRS control unit continuously transmitting error frames and paralyzing the B-CAN network. Replaced the SRS control unit, recoded and matched it to the vehicle. Fault completely resolved.
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.