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 reading the speed of the right rear wheel because there might be a problem with the sensor or its wiring.
The wheel speed sensor detects the speed of the wheel and sends this information to the car's computer. If the circuit is low, it means the sensor might not be sending enough information.
The C120A code indicates a low voltage condition in the rear right wheel speed sensor circuit. This could be due to a faulty sensor, damaged wiring, or poor electrical connections.
• ABS warning light on
• Traction control system may be disabled
• Erratic speedometer readings
• Faulty rear right wheel speed sensor
• Damaged or corroded wiring or connectors
• Poor electrical connection in the sensor circuit
ABS: Anti-lock Braking System
OBD-II: On-Board Diagnostics II
• Inspect the rear right wheel speed sensor and its wiring for damage.
• Check the electrical connections for corrosion or looseness.
• Use a multimeter to test the sensor's voltage output.
• Replace the faulty wheel speed sensor.
• Repair or replace damaged wiring or connectors.
• Ensure all connections are clean and secure.
• Multimeter
• OBD-II scanner
• Basic hand tools
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Focus
• Regularly inspect wheel speed sensors and wiring.
• Keep electrical connections clean and free of corrosion.
• Avoid driving in harsh conditions that may damage sensors.
Sensor Issue
• Do not ignore the ABS warning light; get it checked promptly.
• Drive cautiously if the ABS or traction control is disabled.
• Schedule regular maintenance checks.
Check if the vehicle's warranty covers sensor replacement.
This code is commonly reported in vehicles with high mileage or those exposed to harsh environmental conditions.
Moderate – It affects safety systems like ABS, so it should be addressed soon.
Driving with a malfunctioning ABS system can increase stopping distances and affect vehicle safety.
• Vehicle stationary
• Ignition on
The rear right wheel speed sensor is located near the wheel hub of the right rear tire.
Q: Can I drive with a C120A code?
A: It's not recommended as it affects your ABS system, which is crucial for safe braking.
Q: How can I reset the ABS light?
A: Fix the underlying issue and 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.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.