AU
B170D1B

This DTC indicates the SRS (Supplemental Restraint System) control module detects an open circuit in the Curtain Shield Airbag RH ignition circuit — Seal U

Safety System

This DTC indicates the SRS (Supplemental Restraint System) control module detects an open circuit in the Curtain Shield Airbag RH ignition circuit.

Specifically, the ACU (Airbag Control Unit) continuously monitors the circuit resistance of each airbag inflator.

When the Curtain Shield Airbag RH resistance exceeds the normal range (typically >10Ω or infinite), the ACU registers a 'disconnected' state.

This fault prevents the Curtain Shield Airbag RH from deploying during a side impact or rollover, severely compromising occupant head protection, and continuously illuminates the instrument cluster airbag fault warning lamp.

The B170D1B fault code on the Seal U indicates an open circuit in the right curtain shield airbag ignition circuit. This is a medium-severity SRS fault because the right curtain airbag may not deploy in a side impact or rollover, and the airbag warning light will stay on. Common causes include a loose right-side airbag connector or a faulty curtain airbag igniter. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Right curtain airbag wiring harness connector loose or making poor contact (commonly the yellow connector on the right side of the headliner or B-pillar)
  • 2Right curtain airbag module internal igniter open circuit (broken internal spiral coil or propellant failure causing abnormal resistance)
  • 3Physical damage to the wiring harness (frequent door opening and closing causing a fatigue break in the B-pillar harness, or accidental damage during headliner repairs)
  • 4Oxidation or terminal back-out at the SRS control module (ACU) connector causing loss of communication with the right curtain airbag.
  • 5Vehicle water ingress or high humidity causes internal corrosion in the curtain airbag connector, resulting in excessive contact resistance that registers as an open circuit.
What To Do
  • 1
    Safety preparation: Disconnect the low-voltage battery negative terminal and wait at least 3 minutes to fully discharge the SRS backup power supply and prevent accidental airbag deployment.
  • 2
    Visual inspection: Remove the right-hand A-pillar, B-pillar, and right-hand roof trim panels. Verify the yellow connector (usually marked 'CSAB RH' or similar) is fully locked. Inspect the terminals for oxidation, burn marks, or water ingress.
  • 3
    Resistance measurement: Disconnect the right curtain airbag connector. Use a multimeter to measure the resistance between the terminals on the curtain airbag side. The normal value is 2.0-5.0Ω. If the reading shows infinity (OL) or >10Ω, the curtain airbag is damaged. Replace the curtain airbag.
  • 4
    Harness continuity test: Measure the continuity of the two wires between the curtain airbag connector and the SRS ECU (< 1 Ω). Measure their insulation to body ground and the 12 V power supply (> 10 MΩ) to check for intermittent open circuits.
  • 5
    Reset verification: Reconnect all connectors (ensure they click into place) and restore power. Use VDS or a Launch diagnostic tool to clear the fault code. Perform 'SRS system self-check' or 'collision output check'. Confirm B170D1B does not return and the warning light turns off.
Real-World Cases
BYD DTC AI Analysis

BYD E2 right-side curtain airbag intermittent fault after water wading

✓
A 2019 BYD E2 presented with the SRS warning light illuminated after driving through water during a heavy rain. Scanning revealed fault code B170D1B. Removing the right B-pillar trim showed water stains and green copper corrosion inside the curtain airbag harness connector. The technician cleaned the terminals with electrical contact cleaner, applied conductive protectant, reconnected the plug, and wrapped it with waterproof tape. The technician also checked the drain holes for blockages. The fault cleared following the repair.
BYD DTC AI Analysis

Qin EV curtain airbag not connected after accident repair

✓
A 2019 BYD Qin EV was hit on the right rear. After a third-party shop replaced the right side panel, the airbag warning light came on. Diagnosis found the technician didn't fully insert the yellow curtain airbag connector when fitting the new headliner – it was only pushed in halfway, causing poor contact. Fix: Reseated the connector so the locking tab fully engaged, performed 'Airbag Module Recalibration' under 'Configuration and Settings' with a diagnostic scanner, and cleared the fault codes.
BYD DTC AI Analysis

Chafed E3 wiring harness caused open circuit in right curtain airbag

✓
2020 BYD E3 at 80,000 km: Intermittent airbag warning light and DTC B170D1B. Found the lower B-pillar wiring harness at the door hinge had insulation damage from prolonged friction, the internal wires broken but still making intermittent contact. Repair: cut out the damaged section, soldered in colour-matched high-temperature wire, added corrugated tubing for protection, and rerouted the harness away from metal edges.
Other Seal U Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U overview →
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.