C1573

Code

FIAT C — Chassis

Wheel speed sensor interface error

Brand: FIAT

Type: C — Chassis

Views: UK: 9 EN: 19 RU: 11

AI status

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Page language: EN

Causes

Damaged or disconnected wheel speed sensor
Wiring harness damage (short to battery, short to ground, open circuit, intermittent)
Corroded/poor connector or pin contact at sensor or ABS module
Damaged or missing tone/ring gear (broken teeth, heavy corrosion, contamination)
Faulty wheel bearing or hub causing incorrect sensor gap or mechanical damage
Poor sensor ground or missing reference supply

Symptoms

ABS and/or ESC warning lamp illuminated
Traction control or stability control disabled
Inaccurate or flickering speedometer (depending on vehicle model)
ABS activation abnormal or unavailable under braking
Diagnostic trouble code stored for wheel speed sensor circuit
Possible intermittent fault that appears/disappears with wheel movement or temperature

What to check

Read and record all stored and pending codes and freeze-frame data from ABS and powertrain modules
Visually inspect sensor, tone ring, wiring, and connectors at the affected wheel for damage, corrosion or contamination
Check connector pins for corrosion, bent pins, or moisture; reseat connectors
Measure sensor resistance (for passive sensors) and compare to specification
Verify reference supply voltage and ground at the sensor (for active sensors)
Probe sensor output while rotating the wheel (with vehicle securely supported) using an oscilloscope or multimeter

Signal parameters

Passive (VR) sensor: AC sine waveform; amplitude increases with wheel speed (typical millivolt to volt range depending on speed)
Passive sensor resistance: typical range varies by model (check Fiat specification) — use resistance check only as a rough guide for open/short
Active (Hall/LS) sensor: square wave or digital pulse; typical supply 5 V or 12 V and output switching 0–5 V (model dependent)
Frequency: 0 Hz at rest up to several kHz at high wheel speed (depends on tooth count and vehicle speed)
Expected waveform: clean sine (VR) or clean square pulses (active). Distorted, low amplitude, missing pulses or excessive noise indicate a problem
CAN/vehicle speed messages: wheel speed values should be consistent between wheels; large discrepancies indicate sensor/interface issues

Diagnostic algorithm

Retrieve all ABS/ESC and related fault codes and freeze-frame data; note which wheel or circuit is referenced if available.
Clear codes, perform an initial road/park test to see if C1573 returns; intermittent return helps narrow wiring or intermittent sensor issues.
Visual inspection: check sensor, tone ring, hub/bearing, and wiring route for damage, contamination, crushed wires or pinched sections.
At the sensor connector, check for corrosion, bent pins or water ingress; disconnect and inspect contacts, then reconnect securely.
Measure sensor supply and ground (for active sensors) with ignition on. Confirm proper reference voltage and good ground.
Measure sensor output while rotating the wheel: use an oscilloscope for waveform analysis. For passive sensors check AC amplitude; for active check square pulses and voltage levels.
Perform continuity and insulation checks between sensor wires and chassis/12 V to look for opens or shorts. Wiggle test wiring to reproduce intermittent faults.
Check tone ring condition and sensor air gap. Replace or repair damaged tone ring or adjust gap per specification.
If sensor output is out of specification or inconsistent, replace the suspect sensor and clear codes. Re-test to verify repair.
If sensor and wiring test good but code persists, inspect ABS module connector and wiring harness for damage. Consider module bench test or replacement if internal interface driver is suspected (consult factory service information).
After repairs, road-test and monitor wheel speed signals and ABS/ESC fault memory to confirm the issue is resolved.

Likely causes

Broken/contaminated tone ring or improper air gap
Connector corrosion or wiring open/short at sensor
Failed wheel speed sensor (passive or active)
Intermittent wiring fault at suspension/steering flex point
Loss of sensor reference voltage or ground at ABS module

Fault status

⚠️ Status

ABS/ESC control unit logged C1573 — wheel speed sensor interface error. Fault indicates abnormal, missing or out-of-range wheel speed sensor signal or an electrical interface problem.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours

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