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B163C1B

DTC B163C1B indicates the front passenger side airbag igniter circuit resistance exceeds the normal threshold (typically 2 — Atto 3

Safety System

DTC B163C1B indicates the front passenger side airbag igniter circuit resistance exceeds the normal threshold (typically 2.0–3.0 Ω).

The system triggers this fault upon detecting resistance > 6 Ω or an open circuit.

This fault falls under the SRS (Supplemental Restraint System) passive safety category, specifically indicating a high-resistance fault in the front passenger seat-mounted side airbag or curtain airbag electrical circuit.

High resistance indicates poor circuit contact, a broken wiring harness, an oxidized connector, or an open airbag igniter.

This condition may prevent proper airbag deployment during a collision, constituting a safety-related functional fault.

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Cases Logged
Real-World Cases
BYD DTC AI Analysis

Oxidised seat connector caused intermittent high resistance on Qin Pro DM

✓
A 2019 Qin Pro DM with 32,000 km had an intermittent SRS warning light on the instrument panel. The stored DTC was B163C1B (active). Inspection found green oxide inside the yellow connector under the front passenger seat, and insufficient pin contact pressure. The cause: the vehicle had been driven through water, allowing moisture to seep under the seat. The fix: cleaned the connector with WD-40 Precision Electrical Contact Cleaner, applied conductive grease, and adjusted the terminal spring tension. The fault cleared. A one-week follow-up confirmed no recurrence.
BYD DTC AI Analysis

Open circuit in passenger-side airbag module internal igniter.

✓
2018 BYD Qin PRO (petrol). Replaced the passenger seat assembly after accident repairs. After installation, logged DTC B163C1B. Measured the new seat airbag resistance: open circuit. Disassembly revealed the airbag igniter pins fractured due to stress during transport. Replaced the seatback side airbag module (PN: K8A-5820400). Remeasured resistance: 2.1 Ω. Cleared the DTC, system normal. Do not drop or stack airbag modules.
BYD DTC AI Analysis

Worn B-pillar wiring harness caused resistance drift.

✓
A Qin PRO DM with 58,000 km had the passenger side airbag warning light staying on constantly. Diagnosis found the wiring harness between the seat connector and SRS module had worn through its insulation at a corner of the B-pillar trim, the copper core partially broken with only 2-3 strands still connected. Resistance measured 8.5Ω (unstable). Stripped back the harness, cut out the damaged section, and soldered in 0.5mm² high-temperature silicone wire. Reinforced the harness routing to prevent contact with sharp edges. Fault resolved.
BYD DTC AI Analysis

SRS control module false positive

✓
2019 Qin Pro, no accident history. SRS warning light illuminated suddenly, storing DTC B163C1B. Passenger airbag resistance: 2.0Ω (normal). Wiring harness continuity checked normal. Connectors showed no abnormalities. Suspected internal ACU fault. Upgraded SRS control module software from V1.2 to V1.4; fault persisted. Replaced SRS control module (part no. K8A-3636100), performed online configuration coding, and cleared the fault. Cause: aging of the internal sampling resistor in the control module.
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.