I sure don't see but one. it is up on the down pipe.

I did some searches here about my CEL code p420. Maybe I picked up some different cars, but there were lots of suggestions about using a CEL boss that pulls the back sensor up and out of the stream of exhaust.... thus getting better readings and turning the CEL off.

I saw a great Youtube vid about cleaning the cat... but to get it off, the front half of the system must come off. So that is going to be a bigger job than 1st expected.

So I now have only 2 codes

P420 Cat eff. below threshold
P133 O2 CKT Slow bank 1 sensor 1

I assume the sensor could be causing both, right?

I don't want to throw parts at this thing. Is there a test for the O2? and is there only one?

THe car has 171K miles on it and I have no idea if the PO changed the O2.

 

Two connectors with heat shielding go to the sensors on the exhaust. I thought the downstream sensor was after the CAT.



I am going to put the CEL boss on the btm sensor.

Thoughts from anyone....?

 

got an answer on another forum, and the answer is.... that IS the CAT, or at least the 1st one. Turns out there are 2 CATs. So I have added the CEL boss to the sensor in the bottom of the above picture, cleared the codes and I my fingers are crossed for no CEL and a passing grade at the emissions test.


I will drive it a couple days and check the "pending" codes, if there are none, I will report back and head to do the test.

 

Hi malcolm2,


I have had the same P420 code since I got my S40. I tried the O2 extender, but went cheap and didn't get the Cell Boss, so I still have the code off and on. The real Cell Boss is about 1" taller than the 'spark plug extender' that I used


Let us know if that light stays out.


Jeremy

 

The CEL Boss works as I've used it on my 2001. And you are right, it is the lower O2 sensor under the small cat convertor directly below the turbo. I'm not aware of any test for ohms or continuity on the O2 sensor. The car seems to know if it doesn't switch back and forth properly between lean and rich.

 

The suspense is killing me. My daughter has only driven 40 miles in 3 days.... but the light is still out, and I checked the OBD for pending codes and all is clear.


I had to help her out. I put 40+ interstate miles on it last night and still OBD clear.

 

figure 200-300 miles and you should be good...

 

SUCCESS>>>> went to the testing facility on Tuesday and the car passed. No pending codes, and no CEL. I think it had been about 200 miles since I cleared the CEL and installed the Boss. Spread the word and get yourself a CEL Boss.