AU
C080002

This DTC indicates the ABS (Anti-lock Braking System) electronic control unit detects an operating supply voltage outside the calibrated allowable range (typically 9 — Atto 3

Braking System

This DTC indicates the ABS (Anti-lock Braking System) electronic control unit detects an operating supply voltage outside the calibrated allowable range (typically 9.5V-16V).

In the BYD E5, the 12V low-voltage system powers the ABS module.

The DC-DC converter steps down voltage from the high-voltage battery pack to provide this supply.

If the module detects voltage that is too high (>16V, risking internal ECU circuit damage) or too low (<9V, reducing control accuracy), it logs DTC C080002.

This condition may trigger system protection mechanisms, causing ABS, EBD, ESC, and Automatic Emergency Braking functions to fail or enter a degraded mode.

Troubleshoot this fault immediately, as it affects braking safety.

4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 112V low-voltage battery aging, sulfation, or internal short circuit causes voltage fluctuations or increased internal resistance, resulting in a sudden voltage drop during high-current loads such as ABS pump motor operation.
  • 2DC-DC converter fault: Output voltage regulation failure causes excessively high (>15V) or unstable low-voltage system voltage.
  • 3Poor contact, oxidized or loose terminals, or a burnt fuse holder in the ABS module power supply circuit (constant power B+, ignition power IG1), causing excessive circuit voltage drop.
  • 4Corroded or loose main body ground point (usually located on the left front side member or near the battery tray), causing ABS module reference ground potential drift.
  • 5Faulty internal power management circuit or voltage monitoring chip in the ABS hydraulic modulator, causing false warnings or failure to adapt to normal voltage fluctuations.
What To Do
  • 1
    Connect the diagnostic tool to read the DTC freeze frame data. Confirm the specific voltage value when the fault occurred (to determine if it is a high-voltage or low-voltage fault), as well as related information such as vehicle speed and ABS pump operating status.
  • 2
    Measure the 12V battery static voltage (standard 12.4V-12.6V) and loaded voltage (turn on headlights and air conditioning; must be >12.0V). Use a battery tester to measure the CCA value and internal resistance to determine whether to replace the battery.
  • 3
    Check the DC-DC converter output voltage (standard 13.8V-14.2V). Use an oscilloscope to monitor voltage fluctuations and check for voltage spikes or drops.
  • 4
    Check the ABS module power connector (B25 plug) for backed-out or burnt terminals. Measure the voltage drop at power terminals 1/32 (B+) and 31/16 (IG1) (should be <0.5V). Check the 30A ABS fuse and power relay.
  • 5
    Check the ABS module ground point (G106, usually located on the left front suspension strut tower or chassis rail). Remove the ground wire and sand the contact surface. Measure the ground resistance (should be <1Ω) to eliminate a poor connection.
  • 6
    Inspect the wiring harness insulation for damage and rule out a short to body or intermittent open circuit. Focus on wiring harness protection in high-temperature areas of the motor compartment.
  • 7
    If wiring and power supply are normal, update the ABS module software (if available). If the fault persists, replace the ABS hydraulic modulator assembly with ECU, bleed the system, and calibrate the sensors.
Real-World Cases
BYD DTC AI Analysis

E5: ABS warning light intermittently on while driving; 12V battery aged

✓
Vehicle: 2018 BYD E5, 80,000 km. Symptoms: ABS warning light illuminates intermittently while driving. DTC C080002 (Voltage out of range). Freeze frame shows 11.2V at time of fault. Diagnosis: 12V battery static voltage measured 12.3V, dropping to 11.5V with AC on. Load test: CCA only 40% of rated value, internal resistance 8.5mΩ (excessive). DC-DC output reads 14.0V (normal). Aged battery causes voltage sag when ABS pump operates. Solution: Replaced 12V battery (12V 60Ah). Cleared fault codes; one month follow-up shows no recurrence.
BYD DTC AI Analysis

DC-DC converter output voltage too high caused C080002

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Vehicle: 2019 E5, post-accident repair. Symptoms: ABS and ESP lights on constantly after startup, DTC C080002. Diagnosis: Data stream showed ABS supply voltage at 16.8V, far above normal. DC-DC output also 16.8V; internal voltage regulation circuit fault, likely from accident damage. ABS module undamaged. Solution: Replaced DC-DC converter assembly (integrated with high-voltage distribution box), recalibrated low-voltage system, fault resolved.
BYD DTC AI Analysis

Loose connection at ABS module power connector caused intermittent fault

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Vehicle: 2018 E5, 120,000 km. Symptom: ABS warning light illuminates when driving on rough roads; normal on flat roads. Diagnosis: DTC C080002 stored as history code. Battery and DC-DC converter tested normal. Inspection of ABS module connector B25 revealed burn marks on terminal 1 (constant power B+) and internal looseness. Long-term vibration increased contact resistance, causing voltage drop under high current. Solution: Replaced ABS module power connector (repair kit), re-crimped terminals, applied conductive grease. Fault eliminated.
BYD DTC AI Analysis

Corrosion at body ground point caused voltage fault

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Vehicle: 2019 E5, coastal use. Symptom: ABS warning light on after rain or washing; DTC C080002. Diagnosis: ABS module power supply voltage normal, but resistance between module ground and body measured 3.2Ω (spec <1Ω). Found left front longitudinal beam ground point G106 severely corroded with loose bolt. Cause: Seawater corrosion caused poor ground and reference ground potential drift. Repair: Sanded ground point to bare metal, installed stainless steel ground bolt, retightened, and applied anti-rust paint. Fault cleared.
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.