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B110D

DTC B110D indicates a failure of the Photoelectric Receiving Module in the in-cabin PM2 — Atto 3

Thermal Management System

DTC B110D indicates a failure of the Photoelectric Receiving Module in the in-cabin PM2.5 detection system.

In the BYD Song MAX Green Purification System, the PM2.5 sensor operates on the laser scattering principle: a laser diode emits a light beam of a specific wavelength through an air sample, and airborne particles scatter the light.

The Photoelectric Receiving Module (usually containing a photodiode or photomultiplier tube) captures the scattered light signal and converts it into an electrical signal.

When this module fails, the system cannot accurately detect the in-cabin PM2.5 concentration.

This failure disables the automatic air purification function, disrupts the A/C automatic fresh air/recirculation switching function, and may trigger an air quality detection fault on the instrument cluster.

Although this fault does not directly affect vehicle power or core thermal management functions, it disables the intelligent A/C purification system and impairs in-cabin air quality management during severe smog conditions.

3
Cases Logged
Real-World Cases
BYD DTC AI Analysis

2018 Song MAX: Aftermarket equipment causing communication interference with the photoelectric module

✓
The instrument cluster intermittently displayed 'Air Quality System Fault'. Retrieved DTC B110D. Inspection found the customer had recently installed a dashcam, tapping power directly from the fuse box on the left side of the dashboard and sharing the circuit with the PM2.5 sensor. Poor power filtering of the dashcam generated high-frequency interference, causing abnormal signal transmission in the photoelectric receiver module. Relocated the dashcam power supply to the cigarette lighter socket or a separate fuse, and fitted a ferrite core filter. Fault resolved.
Original source ↗
BYD DTC AI Analysis

2019 Song MAX: PM2.5 sensor optical window contamination failure

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After two years of use, the automatic air purification function failed. Retrieved DTC B110D. Removed the PM2.5 sensor inside the centre console and found an oily dust mixture covering the photoelectric receiver module lens (presumably caused by long-term smoking in the vehicle and use of a poor-quality cabin filter). Cleaning the optical window with anhydrous ethanol was ineffective, as the stains had penetrated internally. Replaced the PM2.5 sensor assembly with a new one (part number: K9C-8121210), performed system calibration, and resolved the fault.
Original source ↗
BYD DTC AI Analysis

2017 Song MAX: Poor wiring harness contact causing intermittent B110D fault

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When driving on rough roads, the dashboard occasionally showed an air quality fault. It was normal when stationary. The scan tool read intermittent fault code B110D. Checked the PM2.5 sensor connector behind the glove box and found slightly oxidised and loose terminals. Cleaned the terminals with electronic cleaner and re-crimped them using a terminal removal tool. Wrapped the connector with electrical tape to prevent loosening. Also checked the LIN line resistance between the BCM and sensor (normal: <1 Ω). The fault did not recur after the repair.
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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.