C0140

Code

Generic C — Chassis

Steering Angle Sensor Circuit

Brand: Generic

Type: C — Chassis

Views: UK: 10 EN: 12 RU: 13

AI status

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Page language: EN

Causes

Faulty steering angle sensor (SAS)
Open, shorted, or damaged wiring between SAS and control module
Corroded or loose connector at the sensor or module
Failed clock spring in the steering column
Power supply or ground problem to the sensor
Loss of communication on CAN/LIN bus used by the sensor

Symptoms

ABS, ESC/Traction control, or stability warning lamp illuminated
Loss of ESC/traction assistance or limited ABS functionality
Steering feels normal but stability systems inactive
Diagnostic trouble codes present related to steering/ABS sensors
Possible intermittent faults that correlate with steering wheel movement

What to check

Scan vehicle for all stored codes and freeze frame data; note related chassis codes
Visually inspect steering column area, sensor connector, and wiring for damage or corrosion
Check fuses and ensure proper battery voltage and chassis grounds
Backprobe sensor connector to verify reference voltage and ground with ignition on
Use a scan tool to read live steering angle sensor values while rotating the steering wheel
Check for loss of CAN/LIN communication if sensor communicates digitally

Signal parameters

Typical supply: 5 V reference or vehicle battery voltage depending on design
Signal types: analog Hall outputs (~0.5–4.5 V, center ≈2.5 V) or digital A/B encoder pulses, or serial CAN/LIN messages
Update rate: commonly 10–100 Hz for live angle reporting
Center (straight-ahead) reading usually around mid-supply; reading changes proportionally with wheel angle
Open/short conditions: open = no signal, short to battery/ground = fixed extreme voltage

Diagnostic algorithm

Read and record DTCs and freeze frame data. Check for related codes (wheel speed, yaw rate, CAN bus).
Visual inspection: open connectors at the steering angle sensor and control module; look for corrosion, bent pins, water, or damage.
Verify power and ground: with key ON, backprobe sensor connector to confirm correct reference voltage and a good ground.
Monitor live data: using a scan tool, observe steering angle values while slowly turning the wheel from lock to lock; confirm values change smoothly and return to center.
Signal verification: use a multimeter/oscilloscope to check analog voltages or A/B pulse outputs; compare to expected behavior (center ~midvoltage, linear change).
Continuity/resistance: with battery disconnected, check continuity of wiring between sensor and module and inspect for shorts to ground or battery.
Check clock spring: if signal drops only when wheel is turned, inspect/measure clock spring continuity and condition; replace if faulty.
Attempt re-calibration: if wiring and sensor signals are valid, perform SAS recalibration/initialization per manufacturer procedure, clear codes and test drive.
Replace: if sensor output is out of specification or intermittent after inspections and calibrations, replace steering angle sensor and retest.
If fault persists after sensor replacement and wiring verified, consider control module fault or professional module-level diagnosis.

Likely causes

Wiring harness chafe or pinched circuit causing intermittent/open
Connector corrosion or bent pins at steering column
Failed SAS due to internal Hall effect/encoder fault
Clock spring failure causing signal loss while turning wheel
Blown fuse or poor ground affecting sensor reference voltage
Module not recognizing sensor because calibration lost after battery disconnect

Fault status

⚠️ Status

Steering angle sensor circuit fault. Stability and ABS-related functions may be limited or disabled. Inspect sensor, wiring, connectors, and perform calibration after repairs.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours