Free OBD-II Code Lookup &
AI Car Repair Assistant
Instantly decode your check engine light. Get detailed explanations, repair costs, and part recommendations for any OBD-II trouble code.
Most Common OBD-II Codes
These are the most frequently triggered check engine light codes. Click any code for a detailed explanation and repair guide.
P0420Catalyst System Efficiency Below ThresholdModerateP0300Random/Multiple Cylinder Misfire DetectedHighP0171System Too Lean (Bank 1)ModerateP0128Coolant Thermostat Below Thermostat Regulating TemperatureLowP0442Evaporative Emission Control System Leak Detected (Small Leak)LowP0455Evaporative Emission Control System Leak Detected (Gross Leak)LowP0430Catalyst System Efficiency Below Threshold (Bank 2)ModerateP0440Evaporative Emission Control System MalfunctionLowP0401Exhaust Gas Recirculation Flow InsufficientModerateP0446Evaporative Emission Control System Vent Control Circuit MalfunctionLowP0301Cylinder 1 Misfire DetectedHighP0302Cylinder 2 Misfire DetectedHighP0303Cylinder 3 Misfire DetectedHighP0304Cylinder 4 Misfire DetectedHighP0172System Too Rich (Bank 1)ModerateP0174System Too Lean (Bank 2)ModerateP0133Oxygen Sensor Slow Response (Bank 1, Sensor 1)ModerateP0135Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)ModerateP0136Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 2)ModerateP0138Oxygen Sensor High Voltage (Bank 1, Sensor 2)Moderate
How It Works
1
Read Your Code
Use an OBD-II scanner to read the diagnostic trouble code from your vehicle's computer.
2
Look It Up
Search for your code above to get a detailed explanation, common causes, and repair steps.
3
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