AU
C058A00

DTC C058A00 indicates the brake booster motor position sensor (MPS1) in the IPB (Integrated Power Brake, intelligent integrated braking/One-Box brake-by-wire system) outputs a voltage signal outside the valid operating range calibrated by the ECU (typically 0 — Atto 3

Braking System

DTC C058A00 indicates the brake booster motor position sensor (MPS1) in the IPB (Integrated Power Brake, intelligent integrated braking/One-Box brake-by-wire system) outputs a voltage signal outside the valid operating range calibrated by the ECU (typically 0.5V-4.5V).

This sensor uses the Hall effect to monitor the absolute angular position of the booster motor rotor in real time and serves as the key feedback component for closed-loop brake boost control.

The ECU sets this fault when the signal voltage remains below the lower limit (<0.2V, short to ground or sensor power loss) or above the upper limit (>4.8V, short to power or internal sensor open circuit) for longer than the calibrated time (typically 200ms-500ms).

Upon fault detection, the IPB enters a degraded mode.

The system cuts off motor assist, requiring the driver to apply greater pedal force (unassisted braking), but retains basic hydraulic braking functions.

Simultaneously, the system illuminates the ABS and ESC warning lamps and disables ADAS functions relying on active braking, such as Automatic Emergency Braking (AEB) and Adaptive Cruise Control (ACC).

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Aging of the internal Hall element in the motor position sensor or demagnetization of the magnetic steel causes the output voltage to drift beyond the normal range.
  • 2Oxidized or backed-out pins at the sensor wiring harness connector (located on the IPB assembly), or worn wiring harness insulation causing a short to ground, short to power, or open circuit.
  • 3IPB ECU internal signal acquisition circuit fault, such as a burnt sampling resistor, damaged ADC module, or abnormal reference voltage source (5V).
  • 4Mechanical seizure of the brake booster motor (e.g., seized bearings or damaged gear set) causes a systematic deviation between the actual motor position and the sensor detected value, triggering a plausibility diagnostic out-of-tolerance fault.
  • 5Strong external electromagnetic interference (e.g., damaged high-voltage wiring harness shielding or installation of high-power aftermarket spotlights) couples into the sensor signal line, causing voltage spikes.
What To Do
  • 1
    Use a VDS or Launch X-431 diagnostic tool to access the IPB system. Read the complete DTC list and freeze frame data. Confirm C058A00 is an active fault, not a history fault. Record key parameters from the time of the fault, including vehicle speed, motor speed, and raw sensor voltage values.
  • 2
    Disconnect the low-voltage wiring harness connector from the IPB electro-hydraulic module (located above the ABS pump body). Visually inspect the connector sealing ring for damage or water ingress. Use a dedicated probe to check the motor position sensor power supply pin (usually a 5V reference voltage) and the signal pin (MPS1 Signal) for oxidation or terminal spread.
  • 3
    Use a multimeter to measure the sensor supply voltage (should be 5V±0.25V) and ground resistance (<1Ω). Plug in the connector and use a back-probe to measure the signal wire voltage. The static voltage should be approximately 2.5V. Turn the ignition switch to the ON position. Listen for a slight turning sound from the motor during the ECU self-check; the voltage should change smoothly between 0.5V and 4.5V. If the voltage remains fixed at 0V, 5V, or battery voltage, a hard fault exists in the wiring or sensor.
  • 4
    If the circuit voltage is normal but the fault code persists, run the IPB brake booster motor self-check procedure (perform the 'Motor Actuation Test' using the diagnostic tool). Simultaneously, monitor the signal waveform with an oscilloscope. A normal waveform shows a PWM signal or analog voltage changing linearly with the motor rotation angle. If the waveform is abnormal while the circuit is normal, this indicates an internal fault in the motor position sensor. Replace the brake booster motor assembly (typically integrated into the IPB).
  • 5
    If the fault persists after replacing the motor, check the IPB ECU software version against the BYD Technical Service Bulletin (TSB) to determine if it requires an upgrade. If the software is up to date, measure the impedance from the ECU sensor signal input terminal to ground/power supply. If the impedance is abnormal, diagnose an ECU hardware fault and replace the IPB electro-hydraulic module assembly with ECU.
  • 6
    After completing the repair, use the diagnostic tool to clear the fault code, perform the 'IPB Bleeding Procedure' (requires two technicians or dedicated pressurization equipment), and perform the 'Position Sensor Calibration' (some models require entering the brake fluid type code, such as DOT4). Finally, perform a road test for verification: check for normal pedal effort, confirm the fault code does not return, and verify the ESC function operates normally.
Real-World Cases
BYD DTC AI Analysis

Song Plus DM-i: IPB connector water ingress after wading caused sensor out-of-range

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A 2021 BYD Song PLUS DM-i suddenly showed ABS and ESP warning lights on the dashboard with a hard brake pedal after driving through heavy rain and flood water. Scanning revealed DTC C058A00 (current fault) in the IPB system. Inspection found the IPB electro-hydraulic module mounted above the right front wheel arch; the low-voltage connector seal had aged, with visible water inside. Resistance between pins 3 (MPS1 signal) and 1 (power) measured 0.8Ω, indicating a short. The technician dried the connector and socket with compressed air, installed a new waterproof seal, sprayed electronic contact cleaner, and reconnected. Although the fault code cleared, the technician replaced the IPB wiring harness connector to eliminate the root cause. After repair, the technician performed IPB bleeding and sensor calibration, resolving the fault.
BYD DTC AI Analysis

Han EV brake booster motor Hall sensor damage causing fixed voltage output

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At 30,000 km, the 2022 Han EV intermittently displayed a 'Check Brake System' warning accompanied by intermittent DTC C058A00. Freeze frame data showed MPS1 voltage fixed at 4.97V (near the 5V supply) when the fault occurred. Technicians verified normal wiring harness continuity and stable 5V reference voltage. They removed and inspected the IPB assembly (Bosch IPB 1.0) and found a dry solder joint on the brake booster motor position sensor, causing the output signal to pull high at certain angular positions. Since the sensor is integrated with the motor assembly and unavailable separately, they replaced the entire IPB electro-hydraulic module (with ECU) to clear the fault.
BYD DTC AI Analysis

Aftermarket headlight modification on Seal caused EMI interference and false fault codes.

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A 2023 Seal developed an intermittent ESC warning light after fitting non-genuine LED headlights, with historic DTC C058A00 stored. Freeze frame analysis showed the fault occurred mainly at night with the headlights on during steering manoeuvres. Inspection revealed the modified headlight's negative cable had been earthed directly to the IPB housing without shielding; the headlight driver's PWM signal was interfering with the MPS1 analogue signal through the ground loop. Relocated the headlight earth wire to the main body earth point and fitted a ferrite core to the IPB wiring harness to suppress high-frequency interference. Cleared the DTC and monitored for one month with no recurrence.
BYD DTC AI Analysis

Denza D9 IPB ECU internal ADC sampling circuit fault

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During PDI of a new Denza D9, the IPB system set DTC C058A00 (current) that would not clear. Voltage measured at the sensor was normal (varying 1.2V–3.8V), but the scan tool showed ECU-received MPS1 voltage stuck at 5.1V (out of range). Confirmed no wiring harness shorts and normal sensor output. Determined the IPB ECU's analogue-to-digital converter (ADC) front-end op-amp circuit was damaged, causing signal acquisition distortion. Replaced the IPB electro-hydraulic module assembly with ECU, performed calibration, and cleared the fault.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.