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 understanding the speed of the right rear wheel because the information it's getting doesn't make sense.
The wheel speed sensor on the right rear wheel is sending signals that the car's computer can't understand or believe.
The C1242 code indicates that the signal from the right rear wheel speed sensor is not matching expected values. This could be due to incorrect phase length, which means the timing or length of the signal pulses is not as expected, leading to an implausible reading.
• ABS warning light on
• Traction control system disabled
• Inconsistent speedometer readings
• Faulty right rear wheel speed sensor
• Damaged or corroded wiring or connectors
• Malfunctioning ABS module
ABS: Anti-lock Braking System
OBD-II: On-Board Diagnostics II
Sensor: A device that detects or measures a physical property
• Inspect the right rear wheel speed sensor for damage
• Check wiring and connectors for corrosion or damage
• Test the ABS module for faults
• Replace the right rear wheel speed sensor
• Repair or replace damaged wiring or connectors
• Replace or reprogram the ABS module if necessary
• OBD-II scanner
• Multimeter
• Wheel speed sensor socket
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Fusion
• Regularly inspect wheel speed sensors
• Keep ABS system components clean and dry
• Address ABS warning lights promptly
Sensor Issue
• Avoid driving in harsh conditions until repaired
• Do not ignore ABS warning lights
• Consult a professional mechanic for diagnosis
Check with your vehicle manufacturer for warranty coverage on ABS components.
C1242 has been a common issue in vehicles with ABS systems, often related to sensor or wiring problems.
Moderate – While the vehicle may still be drivable, the ABS system is compromised, affecting safety.
Driving with a malfunctioning ABS system can increase the risk of accidents, especially in slippery conditions.
• Vehicle stationary
• Engine running
The right rear wheel speed sensor is located near the wheel hub of the right rear wheel.
Q: Can I drive with a C1242 code?
A: It's not recommended as the ABS system may not function properly, increasing the risk of skidding.
Q: How can I reset the ABS light?
A: Fix the underlying issue first, 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.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.