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U01000D

U01000D is a BYD-specific subtype of ISO standard communication fault code U0100 (suffix 0D is a hexadecimal identifier) — Qin Plus

Braking System

U01000D is a BYD-specific subtype of ISO standard communication fault code U0100 (suffix 0D is a hexadecimal identifier).

It indicates a failure to receive a valid data frame via the CAN network between the IPB (Intelligent Power Brake system) and the ECM (Engine Control Module) within a specific cycle (typically 100ms-500ms, depending on calibration).

This triggers the timeout counter to reach its threshold (6th timeout).

In the DM-i hybrid architecture, the IPB must retrieve real-time engine torque, engine speed, and brake energy regeneration request status from the ECM.

Communication interruption degrades the brake energy regeneration function, disables ESC coordinated control, and in severe cases, triggers Limp Home mode.

The basic hydraulic braking function remains available.

The U01000D fault code on the Qin Plus indicates a medium-severity CAN communication timeout between the Intelligent Power Brake system and the Engine Control Module. This can reduce brake energy regeneration and disable ESC coordinated control, though basic hydraulic braking remains available. Common causes include damaged CAN-H/CAN-L wiring or intermittent ECM power/ground faults. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
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Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Intermittent open circuit, short circuit, or short to ground/power in the ECM or IPB CAN-H/CAN-L circuits, especially at damaged wiring harness sleeves in high-temperature areas of the engine compartment.
  • 2ECM power supply circuit fault (including constant power B+ and ignition switch power IG1/IG2) or excessive ground circuit resistance (>1Ω), causing intermittent ECM restarts.
  • 3CAN bus termination resistance deviation between IPB and ECM (standard value 60 Ω, allowable range 58-62 Ω), or branch line length exceeding 0.3 m causing signal reflection.
  • 4Hardware fault in the ECM internal transceiver or IPB gateway module preventing response to Network Management (NM) messages.
  • 5Aftermarket equipment (such as a dash cam or inverter) connected to the CAN bus causes a high bus load rate or signal interference.
What To Do
  • 1
    Use the VDS1000 or DiLink diagnostic tool to perform a 'Vehicle Scan'. Record the U01000D Freeze Frame data and confirm the vehicle speed, SOC, and communication status bits when the fault occurred.
  • 2
    Inspect ECM connector BYD-121PIN (located at the front left side of the engine compartment) and the IPB connector (located in front of the engine compartment firewall). Verify no backed-out pins, oxidation, or signs of water ingress. Apply electronic contact protectant and reconnect.
  • 3
    Measure resistance between OBD diagnostic port pin 6 (CAN-H) and pin 14 (CAN-L): with ignition off, resistance must be 60±2Ω. Measure voltage to ground: CAN-H 2.6-2.8V, CAN-L 2.2-2.4V. Use an oscilloscope to check the waveform for distortion or bit errors.
  • 4
    Check ECM power supply: Measure pin A01 (constant power); voltage should be 12V±0.5V. Measure pin A02 (IGN power) with the ignition switch ON; voltage should be ≥12V. Check resistance between ground pins A03/A04 and body ground; resistance should be <1Ω.
  • 5
    Perform 'Communication Test': Disconnect the ECM connector and connect a terminal resistor simulator (120Ω) in parallel to the IPB-side CAN line. If the fault code changes to U010087 (permanent loss), confirm an internal ECM fault. If the fault code remains U01000D, check the IPB gateway and wiring harness.
  • 6
    After clearing the fault code, perform a road test: simulate regenerative braking at different vehicle speeds (0-60-120km/h) and verify that 'ECM_Torque_Request' and 'IPB_Recup_Torque' in the data stream update synchronously.
  • 7
    If diagnostics confirm an ECM fault, perform 'Online Coding' to match the VIN and immobilizer key. For wiring harness issues, repair the harness, wrap it with waterproof tape (3M Scotch 33+), and secure it in the original clip locations.
Real-World Cases
BYD DTC AI Analysis

Song PLUS DM-i: Intermittent full illumination of instrument panel and hard brake pedal

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Vehicle: 2021 Song PLUS DM-i 110km Flagship, 23,000 km. Symptoms: While driving at highway speeds, the dashboard suddenly displayed "Check Engine System" and "Check Brake System" warnings, the ESC light came on, and the brake pedal went hard but still had braking. Diagnosis: VDS read code U01000D (current fault) from the IPB system; the ECM had no communication. Technicians found fretting wear on pin 45 (CAN-H) of the 121-pin ECM connector—contact resistance spiked to 5 Ω under vibration. Repair: Replaced the ECM connector assembly (part number BYD-3724010), re-crimped the terminals, measured CAN bus resistance at 60 Ω, and road-tested 20 km with no recurrence.
Original source ↗
BYD DTC AI Analysis

Aftermarket dash cam installation caused CAN network failure on Tang DM-i

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Vehicle: 2022 Tang DM-i 252KM Premium. Symptoms: After the owner installed an aftermarket 360-degree surround-view camera, the vehicle frequently set DTCs U01000D and U010104 (lost communication with TCU) and failed to enter READY mode. Diagnosis: Removing the aftermarket equipment cleared the fault. Further inspection found the device tapped power from the OBD port and was spliced in parallel into the CAN bus without authorization. Repair: Removed the non-factory wiring harness, restored the original CAN bus topology, and re-grounded the shield at the BCM. Fault eliminated. Recommendation: Never connect aftermarket devices in parallel to the Powertrain CAN.
Original source ↗
BYD DTC AI Analysis

Qin PLUS DM-i ECM internal transceiver fault causing communication timeout

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Vehicle: 2021 BYD Qin PLUS DM-i 55KM Flagship, 41,000 km. Symptoms: Cold start normal; DTC U01000D triggers at operating temperature (coolant >90°C) with engine shake. Diagnosis: Oscilloscope captured CAN waveforms at the ECM; CAN-H amplitude dropped from 2.8V to 1.2V under high temperature. ECM internal CAN transceiver (TJA1043 chip) thermal stability failure. Repair: Replaced ECM assembly (PN BYD-3610000B), performed online programming and immobilizer matching, flashed IPB control logic with software version 20230815 to increase communication fault-tolerance delay.
Original source ↗
BYD DTC AI Analysis

Song Pro DM-i wiring harness chafes against body, causing intermittent open circuit

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Vehicle: 2022 Song Pro DM-i 110km, 18,000 km. Symptom: Intermittent U01000D on rough roads; normal on smooth surfaces. Diagnosis: Lifted vehicle and inspected chassis harness. Found ECM-to-IPB CAN harness chafing against metal burrs at firewall penetration. Insulation wore through, partially fracturing conductors (only 2 strands remained connected). Repair: Repaired harness using 0.5mm² twisted-pair shielded cable (20mm twist pitch). Installed rubber grommet (part number BYD-33316) at penetration point. Re-secured routing to maintain >50mm clearance from body.
BYD DTC AI Analysis

Seal DM-i IPB gateway module software bug caused false alarm.

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Vehicle: 2023 Seal DM-i 1.5L 121km, 500 km. Symptoms: No driving abnormalities, but instrument cluster reports U01000D after every fast charge; clears after 5 minutes of driving. Diagnosis: Data stream analysis showed high BMS load during fast charging occupied powertrain CAN bandwidth; IPB gateway priority configuration caused ECM message packet loss. Repair: Upgraded IPB control software to V2.3.1 (BYD internal TSB-2023-BR-09) and adjusted Network Management (NM) message transmission cycle from 20ms to 10ms. Fault eliminated.
Other Qin Plus 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.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.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.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.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus 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.