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 is having trouble getting a signal from the sensor that tells how fast the left back wheel is spinning. It's like when your game controller isn't connected properly to your console.
The wheel speed sensor is responsible for providing data on the rotational speed of the wheel to the vehicle's computer. This code indicates an electrical issue with the sensor or its circuit.
The C122B code is triggered when the vehicle's ABS (Anti-lock Braking System) module detects an electrical fault in the circuit of the left rear wheel speed sensor. This could be due to a short, open circuit, or other electrical issues affecting the sensor's ability to send accurate speed data.
• ABS warning light on the dashboard
• Traction control system may be disabled
• Inconsistent or poor braking performance
• Faulty left rear wheel speed sensor
• Damaged wiring or connectors
• Corroded or loose connections in the sensor circuit
ABS: Anti-lock Braking System
OBD-II: On-Board Diagnostics, second generation
• Use an OBD-II scanner to confirm the code.
• Inspect the left rear wheel speed sensor and its wiring for visible damage.
• Test the sensor's electrical connections and continuity.
• Replace the faulty left rear wheel speed sensor.
• Repair or replace damaged wiring or connectors.
• Clean and secure any corroded or loose connections.
• OBD-II scanner
• Multimeter
• Basic hand tools (screwdrivers, pliers)
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Focus
• Regularly inspect wheel sensors and wiring.
• Avoid driving through deep water or muddy conditions.
• Schedule regular maintenance checks.
Sensor Issue
• Do not ignore the ABS warning light.
• Have the vehicle inspected by a professional if unsure.
• Avoid hard braking until the issue is resolved.
Check with your vehicle manufacturer for warranty coverage on ABS components.
This code is commonly associated with vehicles that have experienced harsh driving conditions or have high mileage.
Moderate – It's important to address this issue to ensure proper braking performance.
Driving with a malfunctioning ABS system can increase the risk of accidents. Ensure repairs are made promptly.
• Vehicle stationary
• Ignition on, engine off
The left rear wheel speed sensor is located near the brake rotor on the left rear wheel.
Q: Can I drive with the C122B code?
A: While the vehicle may still be drivable, it's not safe to ignore this issue as it affects the braking system.
Q: How do I reset the ABS light after fixing the issue?
A: After repairs, the ABS light may reset itself. If not, 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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