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 has detected a problem with the size of one or more tires. It's like if your shoes were suddenly too big or too small, and it made it hard to walk properly.
The vehicle's control system monitors the tire diameter to ensure proper operation of systems like ABS and traction control. If the diameter is incorrect, it can affect these systems.
The C0078 code indicates that the vehicle's control module has detected an inconsistency in the tire diameter, which can affect the vehicle's stability and safety systems. This could be due to mismatched tires or incorrect tire pressure.
• ABS warning light on
• Traction control warning light on
• Inconsistent handling
• Mismatched tire sizes
• Incorrect tire pressure
• Faulty wheel speed sensor
ABS: Anti-lock Braking System
OBD-II: On-Board Diagnostics, second generation
• Check tire sizes to ensure they match
• Verify tire pressure is within specifications
• Inspect wheel speed sensors for damage or dirt
• Replace mismatched tires with correct size
• Adjust tire pressure to recommended levels
• Clean or replace faulty wheel speed sensors
• Tire pressure gauge
• OBD-II scanner
• Tire tread depth gauge
$50 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford F-150
• Regularly check tire pressure
• Ensure all tires are the same size
• Inspect tires for wear and damage
Sensor Issue
• Have your tires checked regularly
• Ensure you use the correct tire size for your vehicle
Check with your vehicle manufacturer for warranty coverage on tire-related issues.
This code has been used in vehicles equipped with advanced traction and stability control systems to ensure proper tire function.
Moderate – While not immediately dangerous, incorrect tire diameter can affect vehicle handling and safety systems.
Driving with mismatched or improperly inflated tires can lead to reduced vehicle stability and increased stopping distances.
• Vehicle on level ground
• Tires cooled to ambient temperature
The wheel speed sensors are located at each wheel hub, and the tires are mounted on the vehicle's wheels.
Q: Can I drive with a C0078 code?
A: It's best to address the issue as soon as possible to ensure your vehicle's safety systems function correctly.
Q: How do I know if my tires are the right size?
A: Check the tire size printed on the sidewall of your tires and compare it to the specifications in your vehicle's manual.
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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