Check engine code lookup
Type the code your reader gave you — or a word like misfire, catalytic converter or EVAP. We tell you what it means, whether the car is safe to drive, and what to check — not just the dictionary definition.
Works with p0420, P 0420 or 0420.
We don’t have a page for that code yet. Double-check the exact code (like P0420), make sure it is a generic OBD-II code, and note that some codes are manufacturer-specific and vary by make. A scan tool may show extra manufacturer detail. In the meantime: dashboard warning lights, Can I Drive It?, our diagnostics, or call us and read it out.
What the check engine light and a code actually tell you
The check engine light means the car’s computer has stored a trouble code about a system it is watching. A steady light means a fault has been logged to be diagnosed. A flashing light means a fault is happening right now — usually an active misfire — and you should ease off and get it looked at rather than keep driving. If the flashing light comes with shaking, lost power, smoke, overheating or a strong fuel smell, treat it as urgent; our Can I Drive It? tool walks through exactly that.
A code names a system, not a broken part
This is the important bit. An OBD-II code identifies a system or condition the computer detected — it does not, on its own, prove which part failed. P0420 does not mean “buy a catalytic converter”: it means the sensors either side of the converter do not disagree enough, which can be the converter, an oxygen sensor, an exhaust leak, or the fuel mixture. That is why every code page here has a “what this code does not prove” section, and why we diagnose before anything gets quoted.
How to look one up
Type the code above — p0420, P 0420 and 0420 all work — or search a word like misfire, oxygen sensor or transmission. Filter by system or by how urgent it is. Then read what it means, whether you can drive, and what a proper diagnosis involves.
Meanings shown are for generic OBD-II codes. Manufacturer-specific codes vary by make — always confirm against your vehicle.
Not sure what your code means?
Tell us the code and what the vehicle is doing. We can read it, check the freeze-frame data, and work out what actually needs looking at — before anything gets quoted.