AU
U012608

DTC U012608 indicates the ABS/ESP control unit receives an abnormal CAN bus data frame or detects a checksum failure from the Steering Angle Sensor (SAS) — Seal U

Braking System

DTC U012608 indicates the ABS/ESP control unit receives an abnormal CAN bus data frame or detects a checksum failure from the Steering Angle Sensor (SAS).

This fault is a communication data integrity error, not a simple signal timeout.

The ABS module flags "corrupted data" when it detects a CRC error in the SAS data packet, an abnormal Data Length Code (DLC), or a signal value outside the physically reasonable range.

This fault causes the vehicle's Electronic Stability Program (ESP), Traction Control System (TCS), and Automatic Emergency Braking (AEB) to enter a degraded mode or fail completely.

Some models trigger power limitation (limp mode), severely compromising driving safety.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Steering Angle Sensor (SAS) internal damage causing incorrect data frame transmission or signal drift.
  • 2Sensor wiring harness connector oxidized, loose, or corroded by water ingress (common in flood-damaged or water-exposed vehicles), causing CAN signal interference.
  • 3Chassis CAN bus (powertrain CAN) circuit short to ground, short to power, or poor connection, affecting data communication quality.
  • 4Sensor software version mismatch or missing calibration data prevents the ABS module from correctly interpreting sensor data.
  • 5Internal fault in the ABS/ESP control unit CAN receiver module prevents correct decoding of SAS data.
What To Do
  • 1
    Use the dedicated BYD diagnostic tool (VDS or EDT) to read the complete fault codes. Confirm whether U012608 is a current or historical fault, and check for accompanying communication fault codes such as U010008 and U014004.
  • 2
    Check the appearance of the steering angle sensor under the steering wheel and the condition of the connector. Inspect the connector pins for oxidation, backed-out pins, or signs of water ingress. Clean with electrical contact cleaner if necessary.
  • 3
    Measure the sensor wiring harness: Disconnect the connector and measure the voltage at pins 1-2 (power supply and ground); the voltage should be 12V/0V. Measure the voltage to ground for CAN-H (approx. 2.5-3.5V) and CAN-L (approx. 1.5-2.5V). Use an oscilloscope to verify the CAN waveform is regular.
  • 4
    Check the chassis CAN bus terminal resistance (standard value approximately 60 Ω; individual terminal resistor 120 Ω) and inspect the bus for short or open circuits.
  • 5
    If circuit measurements are normal, remove and replace the steering angle sensor assembly. Note: Do not use non-genuine parts. Sensor models may vary by vehicle configuration.
  • 6
    Use the dedicated diagnostic tool to perform the 'Yaw Rate and Steering Angle Position Sensor Calibration' procedure (BYD dedicated diagnostic tool required; generic diagnostic tools cannot complete this). Follow the prompts to complete steering wheel centering and angle learning.
  • 7
    Clear all fault codes and perform a road test to verify the ESP and ABS warning lights are off and the vehicle has no power limitations.
Real-World Cases
BYD DTC AI Analysis

Replaced damaged steering angle sensor assembly on BYD Song

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A BYD Song had the ESP and traction control warning lights on with no throttle response. Current DTC U012608 (Lost Communication With Steering Angle Sensor). Removed the steering wheel and checked the steering angle sensor connector on the column. Pins 1-2 had normal power and ground, ruling out wiring. Internal chip failure in the sensor was causing data frame errors. Replaced the sensor with an OEM unit and ran the calibration procedure in VDS. Fault cleared, ESP system normal.
Original source ↗
BYD DTC AI Analysis

Song MAX: Wiring Corrosion Repair on Flood-Damaged Vehicle

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A flood-damaged BYD Song MAX displayed "Please check ESP system" on the dash, the ESP warning light was on, and acceleration was weak. Retrieved fault codes U012608, P0228, P2122, and U010008; they returned soon after clearing. Inspection found severe oxidation and corrosion in multiple bus connectors in the engine bay and cabin. Cleaned the steering angle sensor connector and chassis CAN bus connection points, and repaired the damaged wiring harness. After the wiring repair, used a dedicated diagnostic tool to recalibrate the yaw rate system and steering angle position sensor (Launch X431 and Autel tools cannot complete this calibration). Fault completely resolved.
Original source ↗
BYD DTC AI Analysis

Song CAN bus and ECM communication fault

✓
While driving, the BYD Song's engine and ESP warning lights suddenly illuminated with limited power. DTCs U010008 (ECM CAN data corrupted) and U012608 were stored. The technician checked the CAN bus waveform with an oscilloscope and found noise indicating communication faults. Troubleshooting traced this to a poor connection in the CAN bus wiring. After repairing the connection, the technician checked and upgraded the ECM software and recalibrated the steering angle sensor. Power returned and the communication DTCs did not return.
Original source ↗
BYD DTC AI Analysis

Diagnostic tool compatibility issue and sensor calibration

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2020 BYD Song reported DTC U012608. A generic scan tool could not locate the fault or clear the code. The technician switched to a BYD-specific diagnostic tool and found the generic unit accessed incorrect vehicle configuration settings, causing false positives. Disconnect the battery negative terminal for five minutes to clear intermittent faults. For persistent faults, confirm the wiring is normal first, then perform steering angle sensor calibration using the dedicated diagnostic tool; otherwise the fault light stays on even after replacing the sensor.
Original source ↗
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.