AU
U014608

DTC U014608 indicates a CAN communication data length error between the Intelligent Power Brake (IPB) system and the vehicle gateway — Seal U

Braking System

DTC U014608 indicates a CAN communication data length error between the Intelligent Power Brake (IPB) system and the vehicle gateway.

In the UDS diagnostic protocol, U0146 indicates abnormal communication with the Body Control Module (BCM) or gateway.

The suffix '08' specifically indicates an invalid data frame length or a Bus Off state.

This fault occurs when the data packet length sent by the IPB module mismatches the gateway module reception protocol, or when an abnormal CAN physical layer signal causes a data frame parsing failure.

Because the IPB controls brake boost, energy recovery, and Electronic Stability Control (ESC), this fault may limit ABS/ESP functions, cause abnormal brake pedal feel, and disable Automatic Emergency Braking (AEB).

Severe cases compromise driving safety.

When this fault occurs, the vehicle typically enters a degraded mode, limiting specific driver assistance functions.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Internal CAN transceiver fault or software version defect in the IPB module causing transmission of abnormal-length data frames.
  • 2Gateway controller internal fault; unable to correctly parse brake system data from the IPB.
  • 3Poor contact, short circuit, or open circuit in the gateway wiring between the brake system CAN bus (powertrain network) and the body CAN bus.
  • 4Unstable power supply voltage to the IPB or gateway module (below 9V or above 16V) causes the communication chip to malfunction.
  • 5Aftermarket electronic devices (such as dash cams or ambient lighting) interfering with the CAN bus signal, or wiring harness modifications causing abnormal bus termination resistance.
What To Do
  • 1
    Use the BYD VDS diagnostic tool to read the complete fault codes, check for accompanying communication faults such as U0140 and U0121, and record the freeze frame data.
  • 2
    Check IPB module power supply: Measure voltage at connector K148 pin 1 (constant power) and pin 6 (IGN power); voltage must be 12±0.5V. Measure ground resistance at pin 5; resistance must be less than 1Ω.
  • 3
    Check the gateway module power supply: Locate the gateway controller at the lower left of the dashboard and verify normal power and ground at the G2H connector.
  • 4
    Measure the powertrain CAN (P-CAN) bus voltage: Disconnect the battery negative terminal. Measure pins 6 (CAN-H) and 14 (CAN-L) at the diagnostic connector. Terminal resistance should be approximately 60 Ω. Power on the vehicle. CAN-H voltage should be 2.5-3.5 V and CAN-L voltage should be 1.5-2.5 V.
  • 5
    Check the communication wiring between the IPB and the gateway: inspect dashboard wiring harness connectors G2H and G2K for backed-out pins, corrosion, or poor contact.
  • 6
    Update the IPB and gateway module software to the latest version using VDS online programming to resolve software defects.
  • 7
    If the wiring is normal, replace the IPB module, then bleed and calibrate the brake system. If the fault persists, replace the gateway module and reconfigure the network parameters.
Real-World Cases
BYD DTC AI Analysis

BYD Song PLUS DM-i: Intermittent IPB gateway communication loss

✓
While driving, the instrument cluster suddenly displayed "Brake System Fault" and "Check ESP", and the ABS and ESC warning lights illuminated. The fault cleared after a restart but recurred intermittently. VDS retrieved DTCs U014608 and U012108 (Lost Communication with IPB). Inspection found the CAN-H pin on the IPB module G2K connector had backed out 0.5mm, causing poor contact and incomplete data frame transmission when driving over bumps. After reseating the pin and applying conductive adhesive, the fault did not recur during 200km of continuous road testing.
Original source ↗
BYD DTC AI Analysis

Tang DM gateway module hardware fault causing abnormal braking system communication

✓
Vehicle could not enter Ready mode. Instrument cluster displayed "Brake System Fault". VDS could not access IPB system, with DTC U014608 and multiple gateway communication fault codes stored. Measured gateway module G2H connector ignition voltage at only 9.2V, below normal. Found instrument panel fuse box G2H connector loose. Tightened connector; voltage returned to normal but U014608 remained. Replaced gateway module and performed online configuration. Fault resolved. Root cause: damaged internal CAN transceiver unable to correctly parse IPB data length.
Original source ↗
BYD DTC AI Analysis

Han EV: Aftermarket equipment interference caused IPB data length error

✓
After installing a non-genuine dashcam (powered from the OBD port), the owner experienced frequent brake system warnings while driving. The scanner read U014608. Removing the device cleared the fault. Deep inspection revealed an internal circuit fault in the dashcam: it continuously sent abnormal voltage signals to the CAN bus (peaking at 5.5V), causing data frame checksum failures during IPB-gateway communication and triggering length errors. Removing the modified equipment and restoring the factory OBD wiring resolved the fault.
BYD DTC AI Analysis

Qin Pro DM IPB software defect causes communication fault

✓
When starting the vehicle at -10°C, the instrument cluster displayed a brake system fault. VDS read code U014608. Checked the wiring harness and power supply; both were normal. Consulted the BYD Technical Service Bulletin (TSB) and confirmed the IPB controller's early software version had a bug causing abnormal initialization data frame length during cold starts. Performed an IPB software upgrade using VDS (V1.2 to V1.5). Ran 10 cold-start tests after the upgrade; the fault did not recur.
BYD DTC AI Analysis

Song Pro discharged battery causing IPB communication error

✓
Vehicle sat parked for three days and failed to start. Jump-started; the dashboard displayed multiple system faults including U014608 (Gateway data length error). Battery voltage tested at only 10.8V with 45% health. Replaced the battery and cleared most fault codes, but U014608 returned intermittently. Found a 0.3V drop on the IPB module constant power circuit caused by oxidized battery terminals. Cleaned the terminals, applied anti-corrosion grease, and tightened the ground cable. Fault eliminated.
Original source ↗
Other Seal U 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.