AU
C055164

DTC C055164 indicates the IPB (Integrated Power Brake) detects a fault in the Longitudinal Acceleration Sensor signal circuit — Atto 8

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.

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Cases Logged
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Causes
Likely Causes — Atto 8
  • 1Inertial sensor wiring harness connector loose, pins backed out, or terminals corroded: 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 hardware fault: Internal MEMS element damage, zero-point drift, or abnormal signal output causes the output voltage to exceed the IPB recognition range (typically 0.5-4.5V corresponding to ±1.5g).
  • 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 interpret the sensor analog signal.
  • 4Abnormal sensor mounting position or physical damage: Failure to recalibrate the sensor after a vehicle collision or a deformed mounting bracket shifting the sensor mounting angle, or a severe impact damaging 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 (e.g., the sensor communicates via CAN bus instead of a hardwired connection) causes 0x223 message loss or checksum errors.
What To Do
  • 1
    Step 1: Fault code freeze frame analysis and preliminary inspection: Use the VDS2000 or DMS diagnostic tool to read the fault freeze frame. Confirm parameters such as vehicle speed, longitudinal acceleration value, and yaw rate when the fault occurred. Check the vehicle history for collisions, water ingress, or modifications. 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 (should be less than 1 Ω). 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 must be less than 1 Ω. Measure the insulation resistance from the signal wire to power and to ground; resistance must be greater than 10 MΩ. Check the connector terminals for enlarged pin holes or terminal back-out.
  • 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 jumps, drops, or goes out of range, replace the sensor or the 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 (e.g., C055100-C055500 series).
  • 6
    Step 6: Sensor Calibration and System Verification: After resolving the fault, use the diagnostic tool to perform Longitudinal Acceleration Sensor Calibration. Clear the fault codes and perform a road test (including straight-line acceleration, emergency braking, cornering braking, and other driving conditions). Verify the fault code does not recur and the ESC function operates normally.
Real-World Cases
BYD DTC AI Analysis

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

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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

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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 Atto 8 Fault Codes
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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.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.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.