C1143
Wheel Speed Sensor LR Tone Ring Tooth Missing Fault
Chassis Chassis/Safety ABS wheel speed 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The ABS system detected that a tooth is missing from the toothed ring (tone ring) on your left rear wheel, which is like a car's odometer skipping numbers—the sensor can't read speed properly. This causes the ABS module to lose confidence in that wheel's speed data.

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Symptoms You May Notice
3 known symptoms for this code
ABS warning light illuminated on dashboard
Traction control or stability control disabled or malfunctioning
Pulsing sensation in brake pedal during hard braking
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ABS ECU monitors the tone ring's tooth pattern as it passes the wheel speed sensor. It counts tooth intervals and expects a consistent pattern; if teeth are missing or damaged, the sensor signal shows irregular gaps. The ECU detects this anomaly when pulse intervals exceed normal thresholds.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Tooth pulse interval consistency Regular, evenly-spaced pulses Irregular gaps or missing pulse cycles detected
Wheel speed sensor signal amplitude Stable AC signal within 0.5–5V range Erratic or dropout signal indicating tone ring defect
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wheel speed sensor (LR)
Inspect sensor air gap and clean sensor tip; if signal remains faulty, replace the sensor.
2
Tone ring (left rear wheel hub)
Remove wheel, inspect tone ring for missing or broken teeth, and replace the hub or tone ring assembly if damaged.
3
ABS module software or connector
Check all ABS wiring connectors at the module and wheel for corrosion or loose pins; reseat connectors and clear code.