OBD2 Trouble Code Library
Check engine light on? Look up your code below for what it means, the most likely causes, whether it's something you can fix yourself, and a rough cost range if you take it to a shop.
Engine
- P0128
Your engine isn't reaching operating temperature, usually a thermostat stuck open. It drives fine, which is exactly why people ignore it while it quietly costs them fuel every mile.
Emissions
- P0420
The engine computer has detected that the catalytic converter on bank 1 isn't cleaning up exhaust as efficiently as it should. Often the converter itself, but not always — here's what to check first.
- P0455
The most common cause is a gas cap that isn't sealing, and the fix is often free. Here's how to tell whether you're looking at a $20 problem or a $600 one before you pay anyone to find out.
Fuel & Air Metering
- P0171
Your engine is getting more air than fuel, and the computer has run out of room to compensate. Here's what actually causes it, why the cheapest fix is worth trying first, and what a shop repair typically costs.
Ignition System
- P0300
The engine computer has detected that one or more cylinders aren't firing consistently, but couldn't pin it to a single cylinder. Here's what usually causes it, whether it's DIY-fixable, and roughly what repair costs to expect.