What Does Your Check Engine Light Mean?
Get fast, plain-English answers to OBD-II trouble codes and car problems, including whether it is safe to keep driving.
Most Searched Codes
See All Codes →P0420Safe to DriveCatalyst System Efficiency Below Threshold (Bank 1)P0171Fix SoonSystem Too Lean (Bank 1)P0300Stop DrivingRandom/Multiple Cylinder Misfire DetectedP0456Safe to DriveEvaporative Emission System Leak Detected (Very Small Leak)P0128Safe to DriveCoolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
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Common Symptoms
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P0420 CodeP0420 means the Bank 1 catalytic converter tests below its efficiency limit. Learn if it is safe to drive, the usual causes, what to check first and fix costs.Read Guide →
Why Is My Check Engine Light FlashingA flashing check engine light usually means a severe misfire that can overheat the catalytic converter. Here is what it means, what to do now and what to check.Read Guide →
Why Is My Engine Idling RoughA rough idle usually comes from a misfire, a vacuum leak, a dirty throttle body or worn engine mounts. See the clues, related codes and what to check first.Read Guide →