View Full Version : what parameters need to be met to run idle catalyst effiency test?

April 26th, 2009, 01:50 PM
Im still trying to find a way to work around my P0420 problem.

I reworked the exhaust after some input from some other members (put the resonator where the cat. used to be and put a spacer in to pull the O2 sensor a little out of the flow) but that still didnt work.

im wondering what parameters need to be met for the ECM to run the test. im thinking maybe i can work around it, possbly set things up so one of the requirements is never met, possibly increase idle rpm?

April 26th, 2009, 08:12 PM
When you find out please let me know, I got around the P0442 EVAP Small leak (accidently nicked the EVAP canister and had to reseal it) with some tuning changes.

May 3rd, 2009, 04:36 AM
I put a spacer in the rear o2 and havent had a code since...no cat

May 8th, 2009, 01:34 AM
I put a spacer in the rear o2 and havent had a code since...no cat

when i welded in the new O2 bung i spaced it an additional 1/2" out of the exhaust flow(and also downstream of the resonator) & im still having the P0420 code come up. but it only sets from the "Idle Catatlyst Efficiency Test"

regardless, with EFI i shouldnt need to do ANY physical changes. somebody is slacking on the coding & the switching for the MIL/DTC isnt doing what its supposed to.....

February 19th, 2011, 04:11 AM
We have the same problem with the 410 code. Deleting it does absolutely nothing, still sets an engine light.

February 20th, 2011, 02:24 AM
i ended up cheating and buying a set of those 18mm spacers and no more P0420 code. i havent touched this vehicle in over a year (tuning-wise) and it seems to be running fine and gets about 600-700km to a tank of fuel.