AU
C1207

DTC C1207 indicates the torque sensor signal change rate in the Electric Power Steering (EPS) system exceeds the normal threshold — Atto 8

Braking System

DTC C1207 indicates the torque sensor signal change rate in the Electric Power Steering (EPS) system exceeds the normal threshold.

This sensor monitors the magnitude and direction of torque the driver applies to the steering wheel, and steering angle changes.

When the sensor signal experiences sudden changes, drift, intermittent interruption, or a change gradient exceeding the calibrated limit, the EPS control unit cannot accurately calculate the required steering assist and triggers fail-safe mode.

This fault causes a sudden loss of steering assist, heavy steering, or intermittent assist.

In extreme cases, steering wheel binding may occur, severely compromising driving safety.

This fault typically illuminates the EPS warning light and may limit vehicle speed.

5
Cases Logged
6
Causes
Likely Causes — Atto 8
  • 1Torque sensor internal damage, aging, or signal drift
  • 2Torque sensor 8-pin black connector loose, backed-out terminal, oxidized, or poor contact
  • 3Sensor wiring harness short circuit, open circuit, chafing, or electromagnetic interference
  • 4Abnormal EPS control unit supply voltage (below 9V or above 16V) or poor ground connection.
  • 5CAN bus communication fault (abnormal CAN-H and CAN-L line resistance or node fault)
  • 6Mechanical binding in the steering gear assembly causes an abnormal torque signal.
What To Do
  • 1
    Use the dedicated diagnostic tool to read the fault code and record freeze frame data. Check for related fault codes such as C1B0E00 and C106600.
  • 2
    Check the torque sensor (black 8Pin) connector for a secure connection. Inspect the terminals for backing out, oxidation, corrosion, or bending.
  • 3
    Measure the EPS module supply voltage (standard 12V) and ground resistance. Check the CAN-H and CAN-L line resistance (standard approx. 60Ω) and voltage.
  • 4
    Manually turn the steering wheel to check for abnormal noise or mechanical binding. Use the diagnostic tool to verify the torque sensor signal data stream changes smoothly.
  • 5
    Upon confirming the sensor fault, replace the steering gear assembly (the torque sensor is typically not replaced separately). Verify the new part number matches.
  • 6
    Update the EPS system software (if available), and perform the torque sensor zero-point calibration and angle self-learning procedure.
  • 7
    Clear the fault code, perform static and dynamic road tests, and confirm power steering assistance is restored and the fault code does not recur.
Real-World Cases
BYD DTC AI Analysis

BYD E2/E3: Torque Sensor Connector Poor Contact

✓
While driving, the instrument cluster displayed "Check Steering System", the EPS warning lamp stayed on, and steering assist cut out intermittently, making the wheel noticeably heavier. The scan tool retrieved DTC C1207 and related torque sensor fault codes. Inspection found the torque signal (black 8-pin) connector slightly misaligned with oxidised internal terminals, causing intermittent signal interruption. Sanded the ground point, straightened the connector and applied conductive paste; the fault temporarily cleared. The issue returned two weeks later. Replaced the steering gear assembly and recalibrated the torque sensor; fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD HA Passenger Vehicle Torque Sensor Circuit Fault

✓
The EPS warning light illuminated with abnormal steering assist. The scanner retrieved DTC C1207. The technician first inspected the torque signal (black 8-pin) connector and EPS control module connections, finding the connector locking tab damaged and causing poor contact. Further inspection of the torque sensor wiring harness revealed chafing where it passes through the firewall, causing an intermittent short. After repairing the harness damage and replacing the connector, the technician cleared the fault codes with the scanner. After performing the torque sensor calibration and road test, the fault did not return.
Original source ↗
BYD DTC AI Analysis

BYD Song DM: Insulation sensor fault causes EPS power supply failure

✓
While driving, the vehicle displayed a 'Low Voltage Power Supply System Fault' warning. The dashboard lit up with multiple warning lights and power steering failed. Initial checks suggested an EPS fault. Scanned and found DTC C1207 and related communication fault codes. Measured DC output voltage at only 12.8V. Data from the low-voltage iron battery management system showed abnormal charge/discharge fluctuations. Troubleshooting found the leakage current sensor had water ingress from wading (water droplets visible inside after removal), and the charging/distribution assembly had an internal fault. Replaced the charging/distribution assembly and leakage current sensor, tightened all ground points and wiring harness connectors, and updated the vehicle module software. The EPS system returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD S6 power supply node failure causes erratic power steering

✓
After driving at high speed for some time, the transmission warning light illuminated, accompanied by unstable steering assist. Diagnosis revealed poor power supply to the ESP node and main motor node. While initial DTCs pointed to the transmission, further inspection found voltage drop in the power supply line shared with the EPS system. CAN bus measurements revealed intermittent communication interruptions. Resistance in the CAN-H and CAN-L lines from the ESP node to the ACM-ECU exceeded spec (greater than 5Ω). The ESP node power supply fuse holder was burnt, causing unstable voltage to the EPS control unit and triggering DTC C1207. Replaced the power supply line and fuse holder, cleaned the connectors, and resolved the fault.
Original source ↗
BYD DTC AI Analysis

BYD Qin/Tang Series EPS Torque Sensor Multiple Faults

✓
The vehicle developed heavy steering and intermittent power steering failure, with the instrument cluster displaying "Service Steering System." Retrieved DTC C1207. Diagnosis revealed the torque sensor signal jumping at specific angles. Tire pressures checked normal, ruling out external mechanical resistance. Measured EPS module power supply and found the ground point oxidized (resistance greater than 1 Ω). Cleaned the ground point; fault improved but still occurred intermittently when cold. Determined the torque sensor had poor internal thermal stability. Replaced the steering gear assembly, then performed an EPS software upgrade and torque sensor zero-point calibration using a dedicated diagnostic tool. Fault resolved.
Original source ↗
Other Atto 8 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.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.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.
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.