Got a Diagnostic Trouble Code?
If your car is having this issue, there are several possible causes. The only way to know for sure is proper testing.
Choose an available diagnostic time online 24/7. It takes less than 60 seconds, and we'll confirm the details by text.
Common Symptoms
- Check engine light code P0420 (catalytic converter)
- Code P0171 (system too lean) or P0300 (misfire)
- Not sure what an engine code actually means
- Code was cleared but came back
- Multiple codes stored at the same time
What This Could Mean
A trouble code tells you which system triggered a fault — not which part to replace. P0420 means the catalytic converter efficiency is below threshold, but the cause could be the cat itself, an oxygen sensor, or an exhaust leak. P0300 means a misfire was detected, but the cause could be spark plugs, coils, injectors, or a compression issue. Replacing parts based on the code alone without testing is one of the most common ways to spend money and still not fix the problem.
Why Testing Matters
Replacing parts based on a code alone is one of the most common causes of unnecessary repair costs. Proper diagnostics uses the code as a starting point, then performs the testing needed to confirm the actual cause — so the right part is replaced the first time.