Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble reading the speed of the left front wheel. It's like when your bicycle speedometer stops working and you can't tell how fast you're going.
The C122D code indicates a problem with the left front wheel speed sensor, which is responsible for measuring the speed of the wheel and sending this information to the car's computer.
The left front wheel speed sensor is part of the anti-lock braking system (ABS) and traction control system. It monitors the rotational speed of the wheel and sends this data to the vehicle's electronic control unit (ECU). If the ECU detects an irregular signal or no signal from the sensor, it triggers the C122D code.
• ABS warning light on
• Traction control light on
• Inoperative ABS or traction control
• Faulty left front wheel speed sensor
• Damaged sensor wiring or connectors
• Faulty ABS module
ABS: Anti-lock Braking System
ECU: Electronic Control Unit
• Inspect the left front wheel speed sensor and wiring for damage.
• Check the sensor's electrical connections for corrosion or looseness.
• Use a multimeter to test the sensor's resistance and output signal.
• Replace the faulty wheel speed sensor.
• Repair or replace damaged wiring or connectors.
• Replace the ABS module if necessary.
• Multimeter
• OBD-II scanner
• Socket set
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Fusion
• Regularly inspect wheel speed sensors and wiring.
• Avoid driving through deep water to protect sensors.
• Keep the vehicle's undercarriage clean to prevent dirt buildup.
Sensor Issue
• Have the vehicle inspected by a professional if the ABS light is on.
• Avoid hard braking until the issue is resolved.
• Consider regular maintenance checks to prevent future issues.
Check with the vehicle manufacturer for warranty coverage on ABS components.
Wheel speed sensor issues have been common in vehicles with ABS systems since their introduction, often due to sensor wear or environmental factors.
Moderate – While the vehicle can still be driven, the ABS and traction control systems may not function properly, affecting safety.
Driving with a malfunctioning ABS system can increase stopping distances and affect vehicle control during emergency braking.
• Vehicle on a flat surface
• Ignition on, engine off
The left front wheel speed sensor is located near the wheel hub of the left front wheel.
Q: Can I drive with the C122D code?
A: Yes, but it's not recommended as the ABS and traction control systems may not work properly.
Q: How do I reset the ABS light?
A: Fix the underlying issue, then use an OBD-II scanner to clear the code.
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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