What Does C1155 Mean?
This code indicates the ABS control module has detected a general input circuit failure for the left front wheel speed sensor. The module cannot obtain a valid speed signal from the LF sensor. This may be due to an electrical fault, signal quality degradation, or a combination of issues that prevent reliable speed measurement at the left front wheel.
Safety Warning
ABS and traction control are likely disabled. Stopping distances may increase on slippery surfaces. Repair promptly.
Common Causes
35%
Failed left front wheel speed sensor with degraded coil or contaminated magnetic tip
25%
Corroded or damaged wiring in the wheel well area from road salt, moisture, and debris exposure
20%
Excessive sensor air gap from worn wheel bearing or sensor not seated properly
15%
Corroded or loose connector preventing reliable electrical contact
5%
ABS module internal failure on the LF sensor input circuit
Diagnostic Steps
1
Step 1: Inspect the LF wheel speed sensor, wiring, and connector for physical damage, corrosion, or road debris contamination.
2
Step 2: Measure sensor resistance (typical 800-1400 ohms). Compare to the RF sensor reading. Both should be similar.
3
Step 3: Check sensor air gap with a feeler gauge (0.020-0.050 inches). Inspect tone ring for damage.
4
Step 4: Test wiring continuity from sensor to ABS module. Check for shorts to ground and shorts to battery.
5
Step 5: Clear codes, test drive above 15 mph, and monitor LF wheel speed in live data for stability and accuracy.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
This code indicates the ABS control module has detected a general input circuit failure for the left front wheel speed sensor. The module cannot obtain a valid speed signal from the LF sensor. This may be due to an electrical fault, signal quality degradation, or a combination of issues that prevent...
The most common cause of C1155 (Speed Wheel Sensor LF Input Circuit Failure) is: Failed left front wheel speed sensor with degraded coil or contaminated magnetic tip
Typical repair costs for C1155 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS and traction control are likely disabled. Stopping distances may increase on slippery surfaces. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1155 to identify the root cause.
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Quick Info
Category
Chassis
System
Anti-lock Brake System (ABS) / Traction Control System
Difficulty
Type
Manufacturer
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