I have a 2000 Honda Accord V6 sedan (under 100k miles). For two years now I have had a check engine light. Originally I was told it was a CO sensor that was broke. But now when I get the car inspected, the inspector says I have a catalytic error. So off to the mechanic. They replace the catalytic…

Take the car to Autozone and have the codes read. They will do this for free (unless you’re in California, in which case take it to the dealership or an independent mechanic who is not the mechanic you’ve been taking it to, and pay for a diagnostic). Make sure you get the actual codes (it will be a …

It might be a bad O2 sensor. The exact code would provide a clue. Also Google “How to pass a smog test”, there are some good informative links there on this topic.

Have you gone to the dealer ? There are a few instances where the sometimes higher rates of the dealership are offset by actually solving the problem.

The code is P0420. The ‘code definition’ reads: Catalyst System Efficiency Bellow Threshold (bank 1). Car inspections here in Houston are not the kind you can just easy get past like they used to be due to our area-wide high pollution. My next step, if I could not find a solution, was to just tak…

I had this code on a Corolla, a new rear O2 sensor fixed it. Often this code will appear if there is a leak in the exhaust system before the cat.

When my car had that code failure, I did a lot of googling. And, a lot of mechanics said in most cases it is not the cat itself, but the sensors. A review. There is no direct way to test the cat. So, there is a sensor at the input and one on the output. When the car is cold, the convertor cannot…

It could be the sensors, but on newer cars the software can usually tell if the sensor isn’t working. My guess with that code it is the cat that has failed. Or is failing. The cause of the failure could be something wrong with the engine of course. But it wouldn’t be that surprising that a cat…

The check engine light can indeed go on if the gas cap isn’t tightened properly. But the code reader would say the gas cap or something associated with the gas tank vapor capture system was the cause. The code for this car didn’t say it was the gas cap. It says it is the cat converter. There are…

I had this same issue, still coding P0420, with a new cat. But it was aftermarket, and was too small. A larger 1 solved the problem. I have never had a bad o2 sensor set this code on a Honda, just a bad cat.

2000 Honda Accord check engine light mystery

Maintenance/Repairs

Cezont November 8, 2012, 10:06am 9

Could be simpler: My brother had the check engine light go on in his car (Toyota Camry) and his pickup (Dodge). I suggested that after refueling he should tighten the cap till it clicked at least three times. Voila! No more check engine light problem.

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2000 Honda Accord check engine light mystery

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