Code
C167100
HYUNDAI
C — Chassis
Signal Yaw Rate or Acceleration AX or Acceleration AY or Brakepressure State not Valid
Views:
UK: 18
EN: 20
RU: 11
AI status
Completed
Completed
100%
Causes
- Yaw rate (gyroscope) sensor fault or internal failure
- Acceleration sensor (AX/AY) fault or failure of IMU module
- Brake pressure sensor or brake pressure switch fault
- Open/short or intermittent wiring/connectors between sensors and ABS/ESP ECU
- Loss of reference power, ground, or 5V sensor supply
- CAN/LIN communication errors between sensors and control module
Symptoms
- ABS, ESC, or Traction Control warning lamp illuminated
- Stability control disabled, reduced function of ABS/ESC systems
- Unusual or delayed brake feel if brake pressure sensor is affected
- Erratic stability interventions (ABS/ESC activating unnecessarily or not at all)
- Possible diagnostic trouble codes present for related sensors or communication
- Vehicle handling feels unstable at low or high speeds
What to check
- Read all stored and pending DTCs with a capable scan tool (include U-codes and ABS/ESP module codes)
- View live data: yaw rate, lateral/longitudinal acceleration (AX/AY), brake pressure state; note values at key conditions (ignition on, engine off, slow drive)
- Check battery voltage and charging system (low voltage can corrupt sensor data)
- Inspect connectors and wiring harness at IMU/yaw sensor, brake pressure sensor, and ABS/ESP ECU for corrosion, loose pins, damage
- Check for CAN bus errors or loss of communication messages to the ABS/ESP module
- Perform a wiggle test on harness while monitoring live data for intermittent changes
Signal parameters
- Yaw rate (rotation around vertical axis): typical units deg/s; near 0 deg/s when stationary; ranges ±500 deg/s depending on sensor
- Acceleration AX (longitudinal) and AY (lateral): units m/s² or g; near 0 when stationary; short-term spikes during braking/acceleration/turning
- Brake pressure state: digital/state or analog (bar or kPa) depending on vehicle; should change predictably with brake pedal input
- Sensor update rate: IMU typically updates at 50–200 Hz; expect continuous stream without long dropouts
- Reference power: stable 5 V (or specified vehicle reference) to sensor, and solid chassis ground
Diagnostic algorithm
- Connect a manufacturer-capable scan tool. Record all stored, pending, and history DTCs and freeze frame data, then clear codes and attempt to reproduce.
- Monitor live data for yaw rate, AX/AY, and brake pressure state at ignition on, engine idle, and during controlled low-speed maneuvers. Note any implausible values (e.g., large yaw while stationary).
- Verify vehicle battery voltage and charging system; recharge or load-test as needed. Low system voltage may corrupt sensor signals.
- Visually inspect and backprobe connectors at the IMU/yaw sensor, brake pressure sensor, and ABS/ESP ECU. Check for bent pins, corrosion, water intrusion, or damaged wiring.
- With ignition on, measure sensor supply/reference voltage and ground at the sensor connector (expect specified reference, typically ~5 V, and good ground).
- If voltages are correct, monitor signal lines with an oscilloscope or high-speed data logger while performing steering/brake inputs to see realistic signal waveform and update rate.
- Perform a wiggle test on wiring harnesses while observing live data and look for intermittent changes or code returns. Repair any wiring faults found.
- Check CAN bus status and communication with ABS/ESP module (bus errors, message loss). Repair bus issues before replacing sensors/modules.
- If sensors and wiring test good and communications are normal, consider performing module self-tests or reprogramming/updating ABS/ESP software per service bulletin.
- Replace only the failed component confirmed by testing (IMU/yaw sensor, accelerometer module, brake pressure sensor, or ABS/ESP module). After repair, clear codes and perform a road test and sensor recalibration if required.
Likely causes
- Faulty yaw-rate/IMU module (most common for invalid yaw/accel signals)
- Intermittent connector at IMU or ABS/ESP module (pin corrosion, loose terminal)
- Failed brake pressure sensor or wrong brake pressure state signal to ECU
- Damaged sensor harness (pinched, chafed, rodent damage) causing intermittent/short
- Low battery voltage or poor ground causing erroneous sensor readings
- CAN bus fault or lost communication to sensor sub-module
Fault status
Status
Signal Yaw Rate or Acceleration AX or Acceleration AY or Brakepressure State not Valid
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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