C1175
Speed Wheel Sensor LR Input Circuit Failure
Chassis Chassis/Safety ABS/Traction Control 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The left rear wheel speed sensor isn't sending a proper signal to the car's computer, like a speedometer that suddenly stops working. This affects traction control, anti-lock brakes, and stability systems that rely on knowing how fast each wheel is spinning.

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Symptoms You May Notice
3 known symptoms for this code
ABS light illuminated on dashboard
Traction control or stability control warning light active
Uneven braking or wheel lockup during emergency stops
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors AC voltage signals from the left rear wheel speed sensor during vehicle motion. It compares signal frequency and amplitude against expected thresholds based on vehicle speed. A missing, weak, or distorted signal triggers the fault code.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Sensor Signal Voltage 0.5-2.0V AC (variable with wheel speed) Below 0.3V or no signal detected
Signal Frequency 10-1000 Hz proportional to wheel rotation Missing pulses or erratic frequency changes
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wheel speed sensor connector
Clean corrosion and moisture from the connector at the left rear wheel using electrical contact cleaner.
2
Wheel speed sensor wiring harness
Inspect the wiring from the left rear wheel to the ABS module for cuts, abrasion, or loose connections and repair as needed.
3
Left rear wheel speed sensor
Remove the sensor from the wheel hub and replace with a new OEM or quality aftermarket unit if cleaning and wiring checks fail.