I decided to join this forum after this post helped me and I also wanted to share my experience.
I run a set of Mopar polished long tube headers on my midnight blue, 2004 Dodge 1500 Hemi 5.7L, high flow Mopar catalytic converts, Y-Pipe to a single 2.5 inch pipe, FlowMaster low rumble and it goes over the rear axle and stops. All necessary pipe welding was done by me. The Hemi 5.7 also has a cold air intake, a Superchips tuner, 20" stock rims with 305-50-R20 Falken tires. I cut and welded the rear shackles to shorten them and make the truck sit level.
Not even 2 years after I installed the headers, cats, Y pipe, part of the stock tail pipe, FlowMaster low rumble exhaust and tip, I started getting a check engine light or idiot light right before 2011 inspection, of course. Superchips reads DTCs and I was getting the infamous 0420 & 0430, bank 1 and bank 2 efficiency codes (or lack thereof).
I replaced all 4 O2 sensors with Bosch ($29-$59 each) from AutoZone, cleared the DTC, drove it for 50+ miles and still got the 0420 & 0430 codes. Dammit. From here Dodge quoted me $700 on replacement Mopar cats ( you have to buy Y pipe again as well) or $230 each for Magna flow cats (internet) that I have to cut the flange off of the Mopar cats to weld the MagnaFlow cats on. Last option was $500 parts and all to have it done at Joe's in Addision. Good guy, good work but do I need new cats. Hmm. I just spent $100 on a printed board to get my blinker fixed.
Internet! So I found this site. Next I bought the 18mm spark plug non-foulers at AutoZone for $3.99 each. They were in the HELP! section and part number 42009 was one type I bought. I found another set that was a little shorter or longer I can't tell now that I have taken them out of the packages.
I drilled one non-fouler out from each package, screwed them together (undrilled one in front). Then installed 2 / O2 sensors into the non-foulers for Bank1 (passenger side) in back and in front of the cat and the installed the front O2 sensor into a non-fouler on bank 2 (driver side).
The rear O2 sensor on bank 2 has a fatter O2 sensor tip and a larger hole has to be drilled out of the non-fouler. After breaking 2 drill bits, was getting dark outside...I decided to shut it down for the night.
I cleared the DTC and ran it for 50+ miles and NOW getting a 0133 sensor slow response and NOT the 0420 / 0430. Better. So I took out the front non-foulers out from Bank1 front and Bank2 front and installed the O2 sensors, leaving only 1 non-fouler on Bank1 rear.
I cleared the DTCs again and now was getting 0420, ONLY on Bank1! Now we are cooking. Installed a non-fouler on the front O2 sensor on Bank1 and have no codes! I have driven the truck for about 65 miles.
To sum it up -
- Bank1 - Front and back O2 sensors have the non-foulers installed.
- Bank2 - Front O2 sensor has a non-fouler installed.
I hope this rant saves someone the time it took to figure this out!