Code
C1391
MITSUBISHI
C — Chassis
INCOMP.learn neutral(Yawrate)
Views:
UK: 17
EN: 32
RU: 40
AI status
Completed
Completed
100%
Causes
- Yaw rate sensor learning/calibration not completed (procedure not performed or interrupted)
- Faulty yaw rate sensor (internal fault)
- Poor electrical supply (low battery voltage or intermittent power)
- Damaged wiring or poor connector at the yaw rate sensor or stability control ECU
- Incorrect sensor mounting or misalignment after replacement or repair
- Steering angle sensor out of calibration or mismatch with yaw sensor data
Symptoms
- ABS/ESP/VDC warning lamp illuminated
- Stability/traction control functions reduced or disabled
- Diagnostic trouble code C1391 stored in ECU
- Possible reduced vehicle stability interventions during cornering
- No obvious engine drivability fault (code relates to chassis control)
What to check
- Read and record all related ABS/ESP codes and freeze-frame data with a capable scan tool
- Check battery voltage and charging system; ensure stable voltage (preferably >12.6 V) during test and re-learn
- Verify vehicle is on level ground and steering wheel is centered before re-learn (follow OEM procedure)
- Inspect yaw rate sensor mounting for correct orientation, tightness and damage
- Inspect wiring and connectors for corrosion, bent pins, water intrusion or damaged insulation
- Compare live yaw rate sensor output to steering angle and wheel speed sensors while driving with a scan tool (yaw rate ≈ 0°/s when driving straight)
Signal parameters
- Yaw rate (deg/s) — should be near 0°/s when driving straight and change proportionally with steering input
- Yaw rate sensor raw voltage/output (if available) — should be within manufacturer-specified range
- Steering angle sensor (°) — should be centered at straight-ahead and correlate with yaw rate
- Individual wheel speed sensors (km/h or mph) — used to compare expected yaw rate
- Supply voltage to ABS/ESP ECU (V) — stable battery/charging voltage during learn
Diagnostic algorithm
- Connect a diagnostic scan tool that supports ABS/ESP yaw-rate learning and read all stored codes; record freeze-frame. 2) Check battery and charging system; charge battery or use stable power supply if voltage is low. 3) Visually inspect yaw rate sensor and its connector; repair any corrosion or damage. 4) Verify steering wheel is centered and vehicle is on level ground; inspect steering angle sensor and perform its calibration if needed. 5) Monitor live data: confirm yaw rate sensor output is near zero at rest/straight and changes with steering input; compare to steering angle and wheel speed sensors for consistency. 6) Attempt the OEM yaw rate neutral (zero-point) learn procedure with the scan tool; follow exact preconditions (ignition on, vehicle stationary, wheels straight, etc.). 7) If learning fails repeatedly, perform wiring continuity/resistance checks between sensor and ECU and check for CAN bus errors. 8) If wiring and power are good but sensor output is implausible or learning cannot complete, replace the yaw rate sensor and repeat learning. 9) If problem persists after sensor replacement, consider replacing or reprogramming the ABS/ESP ECU per manufacturer guidance.
- After successful learn, clear codes and perform a road test to confirm system operation.
Likely causes
- Yaw rate sensor harness short/open or corroded connector
- Low battery voltage during learning procedure
- Sensor was replaced but re-learn not performed
- Incorrect installation position or loose mounting of yaw sensor
- Steering angle sensor not calibrated, causing disagreement during self-test
Fault status
Status
Incomplete yaw-rate neutral learning detected — yaw rate sensor calibration not completed or failed. Stability control may be limited until the yaw sensor is calibrated or repaired.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email