2000 Civic EX 4 door. The CEL is on and the code says the CC is not performing like it should. Now I just read this in another thread - "After 1996, there are two sensors. The first sensor (before the catalytic converter) is essential to fine tune the A/F ratio. The second sensor (after converter) is used only to check the operation of the converter. If that sensor is faulty, CEL will come on but engine will still run OK."- and I'm wondering if that could be my problem. Does anybody know what that sensor is called, and what it would cost to replace?

Thanks for the help.

 

Get the code (CEL) scanned and let us know what shows up.

 

Will do.

 

Code is P0420


It also had 5 codes for cylinder misfires. P0300 thru P0304


It had a tune up last year, so I'm not sure why the mis-fire codes came up.

 

You could just have some old codes stored. When you have more than one code you need to find out which ones are currently occurring-- do that by clearing the codes then drive until the CEL comes on again. Then scan codes again. The one(s) that reoccur are what is keeping the CEL on.

 

How do I clear the codes?

 

Use the scanner if it has that function, or disconnect the car battery for about a minute with the key off. If you still have the stock radio, make sure you know the radio unlock code as you will need it after disconnecting the battery.

 

No scanner, but I'm taking it to a shop today so I'll have them do it. I've been reading a lot about the P0300 codes and one of the things mentioned is the head gasket might be bad. I hope it's not that.

 

the scanners are pretty cheap and come in handy.

just got the p0420, on mine on thursday night, thinking of just trying to replace the secondary o2 sensor, cause if i gotta change the cat. i would probably replace it anyways. edit, o2 sensor for mine says $95.85.

got a dx, so the cats expensive.

 

The DX manifolds with integral cat often crack. Check that your's isn't. A simple test is to have someone block the tailpipe with a rag while the engine idles. You stay up front and listen for any exhaust hissing out as the pressure builds.