AU
C052801

DTC C052801 indicates the Steering Angle Sensor (SAS) in the Intelligent Integrated Braking System (IPB) detects a steering angle value exceeding the valid system-calibrated range (typically ±720° or ±1440°, depending on vehicle calibration), or the sensor output signal voltage falls outside the normal 0 — Seal U

Braking System

DTC C052801 indicates the Steering Angle Sensor (SAS) in the Intelligent Integrated Braking System (IPB) detects a steering angle value exceeding the valid system-calibrated range (typically ±720° or ±1440°, depending on vehicle calibration), or the sensor output signal voltage falls outside the normal 0.5-4.5V range.

The Electronic Stability Control (ESC) system uses this key input sensor to determine the match between the driver's steering intent and the vehicle's actual yaw rate.

When the steering angle value exceeds this range, advanced driver assistance functions including ESC, ABS, Automatic Emergency Braking (AEB), and Lane Keeping may enter a degraded mode or fail completely, severely compromising vehicle handling stability.

Potential causes include a damaged sensor, an open circuit in the steering wheel clock spring, a Steering Column Control Module (SCCM) communication fault, an abnormal IPB internal signal processing circuit, or a missing SAS zero-point calibration following chassis repairs.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Damaged steering angle sensor (SAS) internal potentiometer or Hall element causes the output signal to drift or remain fixed out of range.
  • 2A broken internal ribbon cable or poor contact in the steering wheel clock spring causes an intermittent open circuit in the sensor power supply, ground, or signal wire.
  • 3Abnormal CAN bus communication between the steering column control module and the IPB (wiring short circuit, open circuit, or abnormal terminating resistor)
  • 4Failure to perform steering angle sensor zero-point calibration and end-stop position learning using the dedicated diagnostic tool after a vehicle collision, chassis repair, or steering system removal and installation.
  • 5IPB (Intelligent Integrated Brake System) control unit internal steering angle sensor signal processing circuit fault, or loss of software calibration data.
What To Do
  • 1
    Connect the BYD VDS2000 diagnostic tool. Read all IPB system fault codes and freeze frame data. Verify if the real-time steering angle sensor value (Steering Angle) displays an invalid value (such as a fixed abnormal value of 8191° or -4096°), and check for related fault codes (such as C052901 Steering Angle Sensor Module Missing).
  • 2
    Inspect the steering wheel clock spring connector for looseness or corrosion. Use a multimeter to measure the continuity of each clock spring circuit (especially the sensor 12V power supply, GND, and signal lines). Turn the steering wheel and monitor the resistance value for abrupt changes.
  • 3
    Measure the voltage at the steering angle sensor connector: confirm the supply voltage is 12V±0.5V, ground resistance is less than 1Ω, and CAN-H and CAN-L voltages to ground are approximately 2.6V and 2.4V respectively. For analog signal sensors, verify the signal voltage changes linearly (0.5-4.5V) as the steering wheel rotates.
  • 4
    Perform the steering angle sensor calibration procedure: center the steering wheel (front wheels straight) and use the diagnostic tool to perform 'steering angle sensor zero-point calibration'. For some models, turn the steering wheel to the left and right limit positions, holding at each position for 3-5 seconds to complete limit position learning.
  • 5
    If the calibration procedure fails or the fault persists, replace the steering wheel angle sensor or steering column control module assembly (on some models, the angle sensor is integrated into the clock spring or steering column module). Perform the calibration again after replacement.
  • 6
    Clear the fault code and perform a road test: Perform slalom and emergency lane change tests on a flat road. Confirm the ESC/ABS warning light remains off. Verify in the diagnostic tool data stream that the steering angle sensor value changes accurately and in real time with steering wheel rotation (symmetrical left and right, reading approximately 0° ±5° when centered).
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro DM steering wheel clock spring open circuit caused steering angle signal to exceed range

✓
The instrument panel ESC warning light stayed on. The diagnostic tool read IPB DTC C052801 (steering angle sensor value out of range). Live data showed the steering angle sensor fixed at 8191° (exceeding the upper limit) and unchanged by steering wheel rotation. Removed and inspected the steering wheel clock spring. Multimeter measurement showed infinite resistance between the sensor power terminal and the clock spring connector, confirming the internal ribbon cable was completely broken. Replaced the steering wheel clock spring assembly (Part No.: BYD-SAS-3602100). Performed steering angle sensor zero-point calibration and limit position learning. Cleared the fault codes and road tested; steering angle values returned to normal and ESC function was restored.
Original source ↗
BYD DTC AI Analysis

BYD Song PLUS DM-i steering angle sensor signal drift on cold start

✓
Owner reported that during autumn and winter, the dashboard occasionally displayed "Service brake system" when starting from cold. DTC C052801 (steering angle value out of range) set. The warning cleared automatically after 5-10 minutes of driving. Inspection found the steering angle sensor connector seal had deteriorated. Condensation formed inside in low temperatures, causing the sensor signal to drift when cold (spiking instantaneously above 900°). Removed the sensor connector, cleaned it with electronic contact cleaner, applied silicone-based conductive grease, replaced the waterproof seal and wrapped it with waterproof tape. Cleared the DTC and monitored for one week. The fault did not recur during cold starts.
Original source ↗
BYD DTC AI Analysis

Steering angle sensor not calibrated after accident repair on BYD Han EV

✓
The steering column assembly was replaced following a front-end collision. After the repair, the ABS and ESC warning lights stayed on and the vehicle wouldn't enter Ready mode (some models restrict this). The scan tool pulled IPB DTCs C052801 and C052901. Inspection showed the technician hadn't calibrated the steering angle sensor. The new sensor's zero point differed from the old unit, so the system flagged the steering angle as out of range. Using VDS2000, they ran "Steering Angle Sensor Zero Point Calibration" with the steering wheel centered and held, then performed "Limit Position Learning" (wheel full left and right lock). After a 15-minute road test, all warning lights went out and the fault codes cleared.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM: Loose IPB module connector causing intermittent communication fault

✓
When driving on rough surfaces, the ESC warning light flashes intermittently with a buzzer alarm; operation is normal on smooth roads. Read DTCs C052801 and U012600 (lost communication with steering angle sensor module). Found the locking tab broken on the main connector for the IPB (Intelligent Integrated Brake System) control unit on the left side of the engine compartment, leaving approx. 2 mm of play. This interrupted the steering angle sensor CAN signal intermittently over bumps. Treated the connector pins (applied conductive grease to prevent oxidation) and secured the connector with cable ties and structural adhesive to ensure full engagement. Cleared the fault codes and road-tested on rough surfaces for 30 minutes. Fault did not return.
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.