2005 Dodge Neon - what is trouble code P0420?

The definition of code P0420 Is Catalyst Efficiency. You may have an oxygen sensor problem or a catalytic converter problem. Your vehicle has 2 oxygen sensors. Have your oxygen sensors scoped to see if they are working properly if they are then you may need a catalytic converter. Depending on your mileage it may be covered under a Dodge emissions warranty. Have it checked by a certified garage first and in the meantime contact your local Dodge dealer and find out the emissions warranty most are 8 yr or 80,000 miles.

A P0420 is when the catalytic converter is acting up and does not like the way the emissions are on the car. It does not have to do specifically with Dodge, since i had the same problem on my '99 subaru impreza. If you have money to fix it up, a catalytic converter can cost between 400 and 1700 bux. I didn't have the money to do that, since im still in school.

Sometimes a bad gulp of gas can do that to the cat converter all of a sudden. If your runnin on regular gas, maybe u got a bad sip from a pump. I changed my grade to 89, and even though it is a little bit more expensive, it is worth it because the car actually runs better and I haven't seen the p0420 code again so far. Its been about 3 weeks since I saw the check engine light, so i haven't had to check with the computer again. My suggestion is to keep the cat converter you have and just clear the check engine light 3-4 days before you go get a sticker if you don't have the money to get a new one.

I hope i helped you..

P0420 Dodge

Some answers were correct, it means cat efficiency. Easiest way to condemn the cat(s) is to warm the engine up until it's in loop mode. Then take a digital thermometer and measure the temperatures on the front and rear of each cat. The back should be at least 75 degrees hotter than the front. Whichever cat(s) fail this test will need to be replaced.

It means you have something wrong with your catalytic converter. If you have the 2.7L motor it could be bad valve seals giving you that error code.

that's just a miss fire in no-1, a bad coil wire will cause more than one miss fire in it,you need to check the plug and wire for that one cylinder,chances are it needs a new set of plugs and wires put on it,and you,ll probably be getting more than one miss fire code on it later on,good luck with it.