AU
U014008

DTC U014008 indicates a CAN data communication integrity check failure between the ABS/ESC control unit and the vehicle gateway controller — Atto 3

Braking System

DTC U014008 indicates a CAN data communication integrity check failure between the ABS/ESC control unit and the vehicle gateway controller.

Data frames sent by the ABS module to the gateway over the Powertrain CAN bus contain CRC errors, out-of-sequence frames, abnormal Data Length Codes (DLC), or protocol format mismatches.

Consequently, the gateway determines the received brake system status data is corrupted.

This fault triggers the brake system fail-safe strategy, degrading or completely disabling functions such as ABS, ESC, EBD, and Autonomous Emergency Braking (AEB).

Simultaneously, the gateway sends multi-system fault warnings to the instrument cluster, severely compromising driving safety.

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Gateway controller internal CAN transceiver chip failure or software checksum algorithm error, preventing the gateway from correctly parsing ABS data frames.
  • 2Physical damage (abrasion, crushing) to the powertrain CAN wiring between the ABS/ESC control unit and the gateway, water ingress and oxidation in the connectors, or excessive contact resistance, resulting in compromised signal integrity.
  • 3ABS/ESC module software bug (such as a calibration defect in early E5 versions) or internal CAN controller hardware fault causing the module to continuously send incorrectly formatted data messages.
  • 4Unstable power supply voltage to the gateway controller (battery voltage below 10V or above 16V, or poor ground) causes data processing timing errors.
  • 5Strong electromagnetic interference (such as high-voltage power distribution system insulation faults or non-OEM retrofitted electrical equipment) causes CAN bus signal distortion.
What To Do
  • 1
    Use the VDS2000/VDS3000 diagnostic tool to read the complete DTC stream. Confirm whether U014008 is a current (Active) or historical (History) fault code. Record vehicle speed, voltage, temperature, and other parameters from the freeze frame data.
  • 2
    Check the power supply voltage (constant B+, ignition IG1) and ground resistance of the gateway controller (typically located under the left side of the dashboard or near the front compartment power distribution box on the BYD E5) and the ABS module. Verify ground resistance is less than 1Ω and voltage is 12-14V.
  • 3
    Measure the terminating resistance between pins 6 (CAN-H) and 14 (CAN-L) of the OBD diagnostic connector (standard value approx. 60Ω, measured with power off). Check the CAN line dynamic voltage (CAN-H 2.5-3.5V, CAN-L 1.5-2.5V). Use an oscilloscope to check for waveform symmetry and noise.
  • 4
    Thoroughly inspect the CAN wiring harness connectors between the gateway and the ABS (such as BJ01, G04, and G05) for water ingress, corrosion, backed-out terminals, or poor contact. If necessary, clean the connectors with electrical contact cleaner, apply conductive grease, and verify the protection rating meets the standard.
  • 5
    Perform control unit software upgrade: Flash the gateway controller and ABS/ESC module with the latest calibration files (Note: E5 2018-2019 models require ABS software version V2.8 or higher to fix an early communication protocol bug).
  • 6
    If the fault persists, verify using the substitution method: first, replace the gateway controller (part number 6A-3600010 or similar). If this fails, replace the ABS/ESC assembly (Note: Code the new module and calibrate the steering angle sensor).
Real-World Cases
BYD DTC AI Analysis

2018 BYD E5 – Gateway module water ingress corrosion caused data validation failure

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2018 E5, 80,000 km. ABS and ESC warning lights illuminated after driving in rain. Fault code U014008. The gateway controller, mounted under the left side of the dashboard, had water ingress from a perished windscreen seal that corroded the circuit board. CAN bus voltage between the gateway and ABS measured normal, but the internal CAN transceiver chip (TJA1043) output distorted waveforms. Replaced the gateway controller and sealed it; also replaced the windscreen seal to prevent recurrence. Fault resolved.
BYD DTC AI Analysis

E5 ABS pump assembly CAN chip damaged, continuously transmitting error frames

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The vehicle failed to engage high voltage; the instrument cluster displayed a brake system fault. The scanner read DTC U014008, which would not clear. Power and ground at the ABS module were normal, but scoping the ABS-side CAN bus revealed heavy error frames. Removed and disassembled the ABS pump assembly; the internal CAN transceiver chip was damaged from overvoltage, continuously transmitting malformed packets and causing the gateway to flag the data as corrupt. Replaced the ABS/ESC assembly and performed calibration. Fault resolved.
BYD DTC AI Analysis

Wiring harness chafing caused a CAN-H short to ground, resulting in an intermittent fault.

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ABS warning light occasionally illuminated when driving on rough roads; normal on smooth surfaces. Read DTC U014008 (intermittent). Inspection found ABS wiring harness in engine bay rubbing against engine mount, with worn insulation causing intermittent CAN-H short-to-ground. When shorted, ABS data signals pulled low, resulting in CRC checksum failures on packets received by gateway; data flagged as corrupt. Re-routed harness and fitted protective sleeving, insulated worn sections. Fault eliminated.
BYD DTC AI Analysis

Software version mismatch caused protocol parsing error

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A 2019 E5 repaired after an accident kept setting U014008 after a second-hand ABS pump was installed. Check showed the replacement was an early hardware revision with software calibration incompatible with the vehicle gateway protocol (data frame length definition mismatch). Hardware part numbers matched, but the software was too old (V2.3). Flashed the ABS module to V2.9; the protocols aligned, the fault code cleared automatically, and all braking functions returned to normal.
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
Common problems reported for Atto 3 →Atto 3 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.