C1141
Wheel Speed Sensor LF Tone Ring Tooth Missing Fault
Chassis Chassis/Safety ABS and Stability Control 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The left front wheel speed sensor detected a missing tooth on the tone ring, which is like a gear with notches that the sensor reads to measure wheel speed. This tooth damage prevents the sensor from accurately counting rotations, confusing the ABS and stability control systems.

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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
Uneven braking or loss of ABS function
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ABS module monitors the frequency and regularity of tone ring teeth passing the wheel speed sensor. It expects a consistent pulse pattern; missing or damaged teeth create irregular gaps in the signal. When detected, the ECU recognizes the anomaly and sets a fault code.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Tooth Pattern Regularity Consistent pulse intervals within 10% variance Pulse gap exceeds 20% of expected interval
Signal Continuity Continuous sensor output at wheel rotation Missing or intermittent signal during rotation cycle
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wheel Speed Sensor (LF)
Remove wheel, unplug sensor connector, unbolt sensor, and install new unit; verify tone ring for visible damage.
2
Tone Ring (LF)
If sensor is good, replace the tone ring by removing the hub assembly and pressing or bolting on a new ring.
3
Front Left Hub Assembly
If tone ring is integral to the hub, replace the entire hub and bearing assembly.