C0278 moderate

Brake Rotor Thickness Variation Detected

The C0278 code means the vehicle's onboard diagnostic system has detected: Brake Rotor Thickness Variation Detected. This is a moderate severity code.

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Keep driving?: Yes, but fix soon
DIY difficulty: moderate
Estimated cost: $150 - $500 (parts and labor)

Read ABS Codes

BlueDriver Bluetooth Pro Scanner

Basic scanners cannot read ABS codes. BlueDriver reads all systems including ABS, SRS, and transmission through your phone.

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Read ABS Codes

LAUNCH CRP123X (Reads ABS + Chassis)

Basic scanners cannot read ABS codes. This one reads all four systems so you know exactly which sensor failed.

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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

Measure rotor thickness at multiple points with micrometer
Check rotor lateral runout with dial indicator
Inspect rotors for visible hot spots or rust ridges
Check wheel hub mating surface for debris or rust
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.