AU
B1708-00

BYD defines DTC B1708-00 as "Seat Driver Recline Rearward Switch Circuit Short To Ground", a body electrical system fault — Seal U

Safety System

BYD defines DTC B1708-00 as "Seat Driver Recline Rearward Switch Circuit Short To Ground", a body electrical system fault.

This fault indicates the Seat Control Unit (SCU) detects an abnormal 0-ohm resistance (short to ground) in the driver seat recline rearward switch circuit.

Possible causes include switch contacts stuck closed, damaged harness insulation causing a short to ground, or connector water ingress.

This fault prevents rearward seat adjustment, causes uncontrolled continuous rearward movement, or disables the seat memory function.

Some third-party data sources incorrectly label this code as "left curtain airbag resistance is 0".

Airbag faults typically use the B10XX-B19XX range or dedicated SRS fault codes, and standard OBD-II assigns B1708 to the seat adjustment circuit.

The B1708-00 fault code on the Seal U indicates a medium-severity fault in the driver seat recline rearward switch circuit, where the Seat Control Unit detects a short to ground. Common causes include a stuck or damaged recline switch, water ingress, or chafed under-seat wiring. The seat may not adjust correctly or memory functions may fail. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Burnt internal contacts, deformed spring plate, or water ingress in the driver seat backrest rearward adjustment switch causing a permanently closed short circuit.
  • 2The under-seat wiring harness chafes due to frequent forward and backward movement, wearing through the insulation and exposing the copper wire, resulting in a short to ground.
  • 3Poor sealing of the seat wiring harness connector allows water ingress after car washing or wading, causing oxidation and resulting in a short circuit between pins or a short to ground.
  • 4Improper modifications (such as floor mat retaining clips or aftermarket seat heating installation) piercing or crushing the seat wiring harness.
  • 5Seat Control Module (SCU) or Body Control Module (BCM) internal drive circuit fault (low probability)
What To Do
  • 1
    Use a dedicated BYD diagnostic tool (BYD-EDS or Launch X-431) to read fault codes, confirm if B1708-00 is a current fault (Active) or a history fault (History), and check for other related seat fault codes.
  • 2
    Visually inspect the wiring harness under the driver's seat and near the seat rails. Specifically check friction points against the metal frame and areas with an excessively small bend radius for damage, discoloration, or signs of water ingress.
  • 3
    Disconnect the seat adjustment switch connector. Use a multimeter to measure the resistance of the rearward adjustment position on the switch side. The normal reading is open circuit (OL). If the resistance is close to 0Ω, replace the switch assembly.
  • 4
    Measure resistance to ground on the wiring harness side (with the SCU and switch disconnected). If continuity to ground exists, inspect the wiring harness section by section. Focus on the seat slide rail retaining clip area and the wiring pass-through hole under the steering column.
  • 5
    If the wiring harness is damaged, repair the insulation with heat-shrink tubing or corrugated conduit, and reposition the wiring harness retaining clips to increase slack. If the switch is shorted, replace the driver's seat multi-direction adjustment switch assembly.
  • 6
    Check the seat control module software version. If necessary, update to the latest version to rule out a false fault.
  • 7
    After completing the repair, clear the fault code. Test the seat fore/aft, up/down, and backrest multi-angle adjustments to verify normal memory function setting and recall.
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro DM seat wiring harness worn through, causing short circuit

✓
Symptoms: Body system warning light illuminated on the instrument cluster. Diagnostic scan retrieved DTC B1708-00. Driver seat backrest rearward adjustment button inoperative. Diagnosis: Wiring harness connector beneath the driver seat found oxidised and loose. Frequent seat movement wore through the harness insulation, allowing internal wires to contact the vehicle body and short to ground. Repair: Replaced the driver seat backrest rearward adjustment switch assembly. Re-wrapped and secured the wiring harness beneath the seat. Fitted a protective sleeve to prevent future abrasion.
Original source ↗
BYD DTC AI Analysis

BYD Song PLUS EV seat switch shorted due to water ingress

✓
Symptom: Driver's seat adjustment failed suddenly while operating, and the memory function stopped working. Diagnostic scanner found DTC B1708-00 in the Seat Control Module (SCU). Disassembly found water ingress inside the side adjustment switch panel (owner spilled a drink). Testing confirmed a short circuit (abnormal continuity) in the rearward adjustment position. Repair: Replaced driver's seat adjustment switch assembly, applied waterproofing to seat harness connectors, and recalibrated memory function. All functions returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM-i seat wiring harness intermittent short circuit

✓
Symptoms: The dealership found historical fault code B1708-00 during a routine service. The owner had not noticed any obvious fault. Diagnosis: intermittent fault. While simulating seat fore/aft movement, the harness experienced excessive tension at extreme positions, causing momentary short circuits. Testing revealed microscopic damage to the harness insulation. Solution: Adjusted seat harness clip positions to increase slack, replaced the damaged harness segment, and installed high-grade abrasion-resistant protective conduit.
Original source ↗
BYD DTC AI Analysis

BYD Yuan Pro seat switch internal contacts deformed

✓
Symptoms: Driver seat backrest would not adjust rearward; forward adjustment worked normally. Scan tool retrieved DTC B1708-00. Removed the switch and tested it: pressing the rearward adjustment button gave a resistance reading near 0 ohms (normal should be several hundred ohms). Disassembled the switch and found the internal contact spring plate had deformed, causing a constant short circuit. Solution: Replaced the driver seat multi-way adjustment switch assembly. Checked the related wiring harness, found no faults, then reinstalled the components.
Original source ↗
BYD DTC AI Analysis

Modified clip pierced the BYD e2 seat wiring harness.

✓
Symptoms: Upon startup, the seat automatically moved to the rearward limit and could not be adjusted back. Diagnosis found the rearward adjustment switch stuck closed. The cause was traced to retaining clips from aftermarket floor mats piercing the wiring harness under the seat, shorting the power and signal wires. Resolution: Removed the improperly installed mat clips, repaired and re-insulated the damaged harness, replaced the seat adjustment switch damaged by the short circuit, and recalibrated the seat position memory function.
Original source ↗
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.