CEL on after CAT was put back on (and info from my co-op at Honda)

UMR Racer · Post by **UMR Racer** » Fri Sep 12, 2008 3:51 am

So I just got back to school from my co-op at Honda in Ohio and I decided to put the cat back on my car. I had a test pipe with a CEL O2 stand-off on it before I changed it. So after I put back on the cat and after driving it for about a week it gave a CEL for cat inefficiency I used the computer at Autozone to clear it and after a few days it came back. I cleared it this time by disconecting the battery but I have a feeling it will be back. Any suggestions on what I could try would be great. On a side note the job at Honda went well and I will be returning for another term next year and they also told me that they should have a position for me when I graduate. I got to work with the new TL and will have a part on the car that I actually designed even if it is small. If anyone is going to school for engineering and/or has a question about the job feel free to ask.

Sean

Post by **stolle** » Fri Sep 12, 2008 5:36 am

why dont you put it back to the way it was, if it worked? or if you must have a cat, for some reason, try using the old stand off o2 deal with the cat and see what happens. what year is the car anywayz?

slammeds2k · Post by **slammeds2k** » Fri Sep 12, 2008 1:29 pm

All I can think of is that you had a test pipe with a cell fix on for so long that the ecu has set the readings that the 2nd o2 sensor was producing as its standard. Then after you switched the cat back on the computer is seeing those readings and it says hold on those arent right and boom you get a cell.
You said that you discnonected the negative on the battery but how long some times it takes a few mins. I would try it again it should work.

risktypes · Post by **risktypes** » Fri Sep 12, 2008 4:26 pm

hrm... it happened when you put the cat back on? what was reason for slapping cat back in?

was your cat damaged?

UMR Racer · Post by **UMR Racer** » Fri Sep 12, 2008 6:40 pm

risktypes;136092 wrote:hrm... it happened when you put the cat back on? what was reason for slapping cat back in?

was your cat damaged?

Well when I was working in Ohio it was just driving to and from work and I liked the louder sound. But now that I'm back in Rolla and I have to drive back home every once in a while the long drives were getting a bit loud. The cat was sitting in a box since I took it off a few months ago.

bildo16 · Post by **bildo16** » Sat Sep 13, 2008 2:07 am

i dont believe that a car (at least hondas) will change operating voltages on their own with out being manually tweaked through software. Can you get the actual code number from the autozone piece of shit? I assume the code you were getting was P0420 which is the code of death for cats. Maybe your cat is bad? You can also moniter the parameters that your ecu considers as efficient on honda scan tool, so it would be interesting to hook it up to the HDS and actually see how far out of spec it is reading.

UMR Racer · Post by **UMR Racer** » Wed Sep 24, 2008 12:13 am

I just checked and cleared the code and it was the P0420. I can put the CEL stand-off back on that I had for the test pipe. Is there any other fix aside from getting a new cat?

stlhondas