Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer thinks the left front wheel sensor is not working right because it's getting strange signals.
The wheel speed sensor is sending signals that don't match expected patterns, indicating a potential issue with the sensor or its connection.
The C123F code indicates that the signal from the left front wheel speed sensor does not match the expected phase length, suggesting a possible sensor malfunction or wiring issue.
• ABS warning light on
• Traction control light on
• Inconsistent speedometer readings
• Faulty left front wheel speed sensor
• Damaged wiring or connector
• Faulty ABS control module
ABS: Anti-lock Braking System
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the left front wheel speed sensor and its wiring for damage.
• Test the sensor's output with a multimeter.
• Replace the left front wheel speed sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Replace the ABS control module if necessary.
• OBD-II scanner
• Multimeter
• Socket set
$100 - $300
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect wheel speed sensors.
• Keep wheel wells clean to prevent debris buildup.
• Ensure wiring and connectors are secure.
Sensor Issue
• Do not ignore the ABS light; get it checked soon.
• Drive cautiously if the ABS system is not functioning properly.
Check vehicle warranty for coverage on ABS components.
This code has been commonly reported in vehicles with high mileage or those frequently driven in harsh conditions.
Moderate – Should be addressed soon to ensure proper ABS function.
Driving with a malfunctioning ABS can be dangerous, especially in adverse weather conditions.
• Vehicle stationary
• Ignition on, engine off
The left front wheel speed sensor is located near the wheel hub assembly on the left front wheel.
Q: Can I drive with the C123F code?
A: It's not recommended as the ABS may not function properly, affecting braking performance.
Q: How do I reset the ABS light?
A: After fixing the issue, use an OBD-II scanner to clear the code and reset the light.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
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Universal · Drive-on ramps
Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
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