AU
C055164

DTC C055164 indicates the IPB (Integrated Power Brake) detects a fault in the Longitudinal Acceleration Sensor signal circuit — Qin Plus

Braking System

DTC C055164 indicates the IPB (Integrated Power Brake) detects a fault in the Longitudinal Acceleration Sensor signal circuit.

This sensor monitors longitudinal acceleration (braking deceleration/driving acceleration) and provides key vehicle dynamic parameters to the ESC (Electronic Stability Control), ABS (Anti-lock Braking System), AEB (Autonomous Emergency Braking), and energy recovery systems.

When the fault triggers, the longitudinal acceleration signal status bit the IPB receives via CAN message 0x223 indicates an error (such as invalid signal, checksum error, or timeout), preventing the system from accurately determining the vehicle motion state.

In severe cases, ESC, ABS, and AEB functions may enter a degraded mode or fail completely.

The instrument cluster illuminates multiple brake system warning lamps, and extreme conditions compromise vehicle braking safety and stability control.

The C055164 fault code on the Qin Plus indicates a fault in the longitudinal acceleration sensor signal circuit detected by the Integrated Power Brake system. Severity is medium, as ABS, ESC, AEB, or energy recovery functions may be reduced if the vehicle cannot read acceleration data correctly. Common causes include loose or corroded sensor/IPB connectors or a faulty acceleration sensor. The first fix is to visit an authorised dealer for diagnosis. Typical repair cost data is available from 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Loose inertia sensor wiring harness connector, backed-out pins, or corroded terminals: Poor contact at the IPB assembly or independent longitudinal acceleration sensor connector (depending on vehicle configuration). This commonly occurs after driving through water, driving on rough roads, or a collision.
  • 2Longitudinal acceleration sensor fault: Internal MEMS element damage, zero-point drift, or abnormal signal output causes the output voltage to exceed the IPB recognition range (typically 0.5-4.5 V corresponding to ±1.5 g).
  • 3IPB internal signal acquisition circuit fault: The 5V sensor reference power supply inside the IPB module has a short or open circuit, or a damaged signal acquisition ADC circuit fails to correctly process the analog sensor signal.
  • 4Abnormal sensor mounting position or physical damage: Failure to recalibrate the sensor after a vehicle collision or a deformed mounting bracket shifts the sensor mounting angle, or a severe impact damaged the sensor's internal vibrating beam.
  • 5CAN network communication interference: Abnormal network impedance, electromagnetic interference, or a terminating resistor fault between the IPB and the sensor (if the sensor communicates via CAN bus rather than a hardwire) causes 0x223 message loss or checksum errors.
What To Do
  • 1
    Step 1: DTC freeze frame analysis and preliminary inspection: Use the VDS2000 or DMS diagnostic tool to read the DTC freeze frame. Confirm parameters such as vehicle speed, longitudinal acceleration, and yaw rate at the time of the fault. Check the vehicle for a history of collision, water ingress, or modification. Visually inspect the IPB assembly and wiring harness for damage.
  • 2
    Step 2: Power supply and ground circuit inspection: Disconnect the IPB connector (or independent sensor connector), check the sensor supply voltage (standard: 5V ±0.25V), check the ground wire resistance (must be less than 1Ω), and confirm the reference voltage is stable without fluctuation. If the voltage is abnormal, repair the wiring harness or replace the IPB.
  • 3
    Step 3: Signal circuit continuity and insulation test: Use a multimeter to measure continuity between the longitudinal acceleration sensor signal wire (usually marked LA-G or LongAccel) and the IPB; resistance should be less than 1Ω. Measure the insulation resistance from the signal wire to power and ground; resistance should be greater than 10MΩ. Check the connector terminals for spread or backed-out pins.
  • 4
    Step 4: Sensor signal waveform verification: Connect an oscilloscope and monitor the sensor output signal waveform while the vehicle is stationary and during acceleration/braking. The normal signal is a stable DC voltage (approximately 2.5V when stationary). Voltage increases during hard acceleration and decreases during hard deceleration. If the signal spikes, drops out, or goes out of range, replace the sensor or IPB assembly.
  • 5
    Step 5: IPB communication and software check: Verify the IPB CAN-H (2.5-3.5V) and CAN-L (1.5-2.5V) waveforms are normal; check the IPB software version and flash the software if a technical bulletin requires an upgrade; check for related combination fault codes (such as the C055100-C055500 series).
  • 6
    Step 6: Sensor calibration and system verification: After repairing the fault, use the diagnostic tool to perform the Longitudinal Acceleration Sensor Calibration. Clear the fault codes and perform a road test (including conditions such as straight-line acceleration, emergency braking, and braking during turns) to confirm the fault code does not return and the ESC operates normally.
Real-World Cases
BYD DTC AI Analysis

Signal Drift in Song Plus DM-i Due to IPB Connector Corrosion After Water Wading

✓
A 2021 Song PLUS DM-i showed "Brake System Fault" after driving through heavy rain and flood water. Scanner read DTC C055164. The IPB sits on the left side of the engine bay; its wiring harness connector seal had degraded, letting water in that oxidised the longitudinal acceleration signal terminal and created contact resistance (reference voltage dropped from 2.3V to 1.8V). Cleaned the connector, applied conductive paste, and replaced the waterproof seal. Fault resolved.
BYD DTC AI Analysis

Seal 6 DM-i fault after accident repair: calibration not performed

✓
Following front-end collision repairs that replaced the front bumper and wiring harness, the instrument cluster continuously displayed C055164. Diagnosis revealed the IPB had been replaced but technicians had not performed the sensor zero-point calibration. Ran the 'Longitudinal Acceleration Sensor Calibration' procedure using VDS with the vehicle stationary and level. Cleared the fault code after calibration; ESC function returned to normal.
BYD DTC AI Analysis

Faulty 5V power module inside IPB caused abnormal signals

✓
A Qin PLUS DM-i with 80,000 km logged DTC C055164. The IPB’s 5V reference supply to the longitudinal acceleration sensor was jumping randomly between 3–5 V. An external stable 5 V supply restored normal sensor signal, isolating the fault to the IPB’s internal power management chip. Replaced the IPB assembly (part number possibly 3568110-XX) and performed online matching. Issue resolved.
BYD DTC AI Analysis

Wiring harness chafing caused intermittent open circuit in the signal circuit

✓
Vehicle intermittently logs C055164 over speed bumps or rough roads; normal on flat roads. Inspection found the IPB wiring harness chafing against body sheet metal at the firewall penetration. Long-term wear damaged the insulation on the longitudinal acceleration signal wire, causing momentary short to ground over bumps. Repaired the wiring, rerouted and secured the harness, and added anti-abrasion sleeving. Fault has not returned.
Other Qin Plus Fault Codes
B1108For 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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus 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.