Brake Rotor Thickness Variation Detected
What does C0278 mean?
The C0278 code means the vehicle's onboard diagnostic system has detected: Brake Rotor Thickness Variation Detected. This is a moderate severity code.
Common Symptoms
- Pulsating brake pedal during braking
- Steering wheel vibration when braking
- ABS or brake system DTC stored
- Braking feels uneven
- Intermittent brake shudder at highway speed
Probable Causes (Ranked by Likelihood)
- Warped or unevenly worn brake rotors Very High
- Lateral rotor runout from improper installation High
- Rust buildup on rotor braking surface Moderate
- ABS sensor misinterpreting rotor variation as wheel speed change Low
Step-by-Step Diagnostic Procedure
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Measure rotor thickness at multiple points with micrometer
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Check rotor lateral runout with dial indicator
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Inspect rotors for visible hot spots or rust ridges
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Check wheel hub mating surface for debris or rust
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Compare ABS wheel speed data for variations
Frequently Asked Questions
What causes brake rotors to warp?
Rotors warp from uneven heating caused by aggressive braking, dragging brake pads, or improper lug nut torque. Over-tightening lug nuts is a very common cause of rotor warping.
Should I resurface or replace warped rotors?
If the rotors have enough thickness remaining, they can be resurfaced on a brake lathe. If they are at or below minimum thickness, replacement is required.
How do I prevent rotor warping?
Use a torque wrench to tighten lug nuts to the specified torque, avoid excessive hard braking, and allow brakes to cool before extended parking. Proper break-in of new pads also helps.