2004 Honda Accord EX 2.4L Engine Light On with P0420 Code - What Does It Mean?
I recently purchased a 2004 Honda Accord EX with a 2.4-liter engine and 50,000 miles. The car has an automatic transmission. About three days ago, I added a fuel injector cleaner to the gas tank. The next day, when I tried to start the vehicle, the check engine light illuminated. I took it to AutoZone for a diagnostic scan, which revealed code P0420 — indicating a faulty catalytic converter. After driving approximately 350 miles and using that entire tank of fuel with the cleaner, the check engine light turned off on its own. However, I'm now wondering whether this is a temporary issue or if there's an underlying problem. Should I still schedule a professional inspection? What could be causing this P0420 code despite the light turning off automatically?
It's advisable to stop using fuel additives like injector cleaners and monitor if the P0420 code reappears. Fuel additives can interfere with catalytic converter performance or sensor readings, especially in older vehicles such as the 2004 Honda Accord EX.