pintobronco

Installed Decat pipe a couple of weeks ago and CEL came on. Searched this site and found that is the usual reaction to the decat. However my mechanic buddy and checked the code. 420 which is cat failure. So in a moment of "try anything" we put the old upstream 02 sensor in the downstream position. Guess what? No CEL. Have driven back and forth to work last three days and still no CEL.... fingers crossed.

CaymanRotary

Keep us posted, didnt think there was a way to solve that code running without a cat.

delhi

As in relocating the upstream o2 sensor? That would leave the bung hold open. Or was it a swap?
Wouldn't that trigger different code(s)?

BigCajun

iTrader: (1)

Did you disconnect the battery?
Mine would sometimes go for weeks without a CEL, sometimes a couple of days.

I can't think of a logical reason why one O2 sensor would read differently.than the other unless they are made to read differently.
If that's the case you could be opening up a can of worms on the upstream.

Loki

iTrader: (1)

The front O2 is a wideband. I wouldn't mess with it. You might not have a code, but you actually need the front O2 to be where it is for the car to manage the engine properly.

CaymanRotary

On a straight pipe setup? Why would it matter? You could be right but unsure why position of that sensor would matter with no cat and the exhaust flow still the same.

CaymanRotary

This is true. That code will stay off sometimes for quite a while.

pintobronco

No left upstream 02 sensor in place. Just removed downstream sensor and replaced with an upstream 02 sensor. One that had failed.

CaymanRotary

Interesting... that's pretty clever. The rear O2 sensor is not really important like the front one is. Using two fronts might work but have to see. Would still think it would just trigger some other exhaust code eventually.

pintobronco

SORRY IF i WASN'T CLEAR. NEW UP STREAM 02 SENSOR IN PLACE....used old failed upstream 02 sensor in downstream position. CEL still out. No code.

pintobronco

No didn't disconnect battery. No 20 pumps. Just put failed upstream 02 sensor in the downstream position. Still no CEL and no code after driving to work all week.

pintobronco

SORRY IF i WASN'T CLEAR. NEW UP STREAM 02 SENSOR IN PLACE....used old failed upstream 02 sensor in downstream position. CEL still out. No code.

pintobronco

Fingers crossed...

CaymanRotary

Did you reset the codes or did it go off by itself?

pintobronco

Reset.....but have driven back and forth to work all week and no CEL.

CaymanRotary

It can sometimes take a while for that code to come back but sounds promising. If this works I might try it.

pintobronco

The upstream 02 sensor that we used was not showing any value...0, so replaced with new one. That old one is the one we put in the downstream position but it was showing 1400* at 2500 rpms. Hopefully it is fooling the ECU and will continue. Only time will tell. I'll get back on this in a couple of weeks or when the CEL comes on.

Capt.Tightpants

Me, too. That cel is what's holding me back from removing the cat.

delhi

If this works you might' receive an award for solving a 17 year old problem!

pintobronco

Maybe, we will see after a couple of weeks/

pintobronco

Maybe someone else could try. just replace the downstream sensor with an Upstream one. See if it works.

pintobronco

Bring on the awards. Cash only.....CEL still out after 700miles of back and forth to work and over to the Coast and back. Wooohooo....fingers crossed.

pintobronco

Out again this morning and no CEL. Running great.

boricua13

hmm, might have to place an order soon

pintobronco

Still no CEL. 800 miles and continues to work just fine.