Wheel Speed Sensor LF Tone Ring Tooth Missing Fault
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.
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.
| 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 |
Code C1141 is classified as a serious fault. If your check engine light is flashing — not just steady — pull over safely and do not continue driving. A flashing CEL indicates an active misfire or critical failure that can cause catalytic converter damage within minutes or permanent engine harm within miles. Contact a certified mechanic immediately. Do not attempt roadside repairs on high-severity codes unless you are trained to do so.
Once the fault is repaired, C1141 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.