C0250

Code

Generic C — Chassis

ABS wheel speed sensor 'A' circuit malfunction

Brand: Generic

Type: C — Chassis

Views: UK: 21 EN: 26 RU: 19

AI status

Completed

ready

Completed 100%

Page language: EN

Read stored DTC(s) with a scan tool and record freeze-frame/live-data for wheel speed channels
Visually inspect the suspect sensor, wiring and connector for damage, corrosion, or contamination
Check for loose or damaged tone ring/reluctor and any missing/metallic debris
Perform continuity and resistance checks of the sensor wiring to the ABS module
Measure sensor supply/reference voltage and ground at the connector (for active sensors)
Probe sensor output while spinning the wheel (oscilloscope or multimeter AC for passive sensors; scope preferred)

Passive (variable reluctance) sensors: AC sine output when wheel spins, typically millivolt to 0.1–1.5 V AC depending on speed; resistance commonly ~800–2000 Ω (varies by vehicle)
Active (Hall/electronic) sensors: require reference 5 V (or vehicle-specific supply) and produce a digital/square 0–5 V or 0.2–4.8 V pulse; sensor supply current typically
Frequency proportional to wheel speed (0–~2000 Hz depending on wheel speed and tooth count)
Open-circuit: infinite resistance; short to ground/power: near 0 Ω or stuck voltage on output

Connect a scan tool, record the exact C0250 occurrence(s), and note which wheel is identified as sensor 'A' per vehicle manufacturer documentation.
Visually inspect the sensor, connector, wiring, and tone ring at that wheel. Repair obvious damage and remove debris.
Unplug the sensor connector and check for corrosion, bent pins, or pushed-out terminals. Clean and secure connector.
Measure sensor resistance (with ignition off). Compare to vehicle spec; open or shorted reading indicates a bad sensor.
With ignition on, check sensor reference voltage and ground (active sensors). Verify correct supply present.
Spin the wheel by hand (or lift vehicle safely and spin wheel) and measure output: AC voltage for passive sensors or digital pulses for active sensors using an oscilloscope or multimeter (if capable).
Perform a wiggle/handling test on the harness while watching live data for intermittent signal dropouts.
Check continuity from sensor connector to ABS module connector for opens/shorts; repair any wiring faults found.
If available, swap the suspect sensor with a known-good sensor from another wheel and retest to isolate sensor vs. wiring/module.
After repairs or sensor replacement, clear codes and road-test while monitoring wheel speed channels to confirm normal operation.
If wiring and sensor test good but fault persists, follow manufacturer procedures for ABS module driver testing or replacement.