P0420 Catalyst Below Threshold on bank 1. This came on my truck. Im assuming the cat is bad correct?


2004 F-150 XLT 5.4 SuperCrew(New Body Style)

 

Yes. If you've got less than 80,000 miles, it'll be covered under federal emissions warranty.

 

That's right, cuz faulty HO2S sensors do not produce the DTCs P0420 and P0430. The sensors must all be tested and shown to be reliable before the Catalyst Monitor can be called by the Executive. This is part of the HO2S monitor sequence.

If your under 80,000 miles, -take it in and have it fixed at the dealership, -it's free. Falls under the emission warranty everyone has on their vehicles - Just don't erase that code lol.

Edit:

Crap! Quintin beat me

 

Thanks guys! Unfortunately I bought the truck without the stock cats, someone replaced them and did a crappy job on the welding. Im just gonna hollow them out and have my buddy tune it for me.

 

Oh, well scratch my post then lol. A bad weld job WILL promote that code as well. When welding, - a Flux Cored MIG can be a PITA, but it can be done off course. Although, a little gas added in the mix can go along way

Keep in mind, just because she's rusty under there, doesn't mean the pipes aren't a certain grade of stainless.

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Your buddy tunes AF's/Trans tables ? Or do you mean delete lol.

Yea, a professional tune is needed to re-calibrate for additional flow,- or THAT addition can work against.

 

yea, i had my cats replaced with magnaflow cats, the guy did a half arsed job of welding and they had all kinds of leaks, but i did the gotts 02 mod (in my photo album) and took the codes right off there!!!

 

when troyer put togther my setup it came with long tubes, mac hiflow etc. He said it was normal to throw p0420/0430 codes with that setup. Said it does it on his wifes truck too and my truck only has 11K miles on it and sure has **** it does it at least once a week. WHO KNOWS!

 

Hey guys i got this code showing up too. Im confused on what bank 1 means. JBrew is what your saying that the vehicle computer will test the HO2S sensors and make sure they are working good before it will throw the P0420Code.

And are these the HO2S sensors you are talking about?





and are both of these things cats or what? To me the back one looks like a cat but i dont know what the front one is.

 

Yes, -there's more to it tho. The following sensors must be tested and shown to be good before the Catalyst monitor can even be run:

HO2S - Heated Oxygen Sensors
ECT - Engine Coolant Sensor
IAT - Inlet Air Temperature
MAF - Mass Air Flow Sensor
TPS - Throttle Position Sensor
VSS - Vehicle Speed Sensor
CKP - CranKshaft Position sensor.


Also, this sequence must be complete for the same -


HO2S monitor tests complete and no DTCs
No Fuel Trim DTCs
EGR Monitor Complete
No Misfire DTCs
No SAIR (Secondary Air Pump) stuck on DTCs (where fitted.)

Yes , sensors are second back both banks.

Catalyst and HO2 Monitors are different/seperate

 

First one is precat, second is your actual cat. On my truck I told it to only monitor the first O2 sensors so the ECM can see rich lean. However I dont care what my cats do, I plan to run long tubes with no cats.

 

What does Bank 1 mean?

 

Long tubes and one High Flow per side is about perfect - NO DTC's , No need for delete or eliminators. They just can't leak. That's what I run now without custom tuning, -I'm still running the factory tune and can pull tree trunks from the ground, -plenty of jump down low.

I ran with just forward cats for awhile, this alone satisfies the monitor, but again ,- I had no leaks. If she leaks, well that's not very efficient lol.

BTW- Both systems sound bad ***

The EGR has to be tight -



Bank one = Passenger side

This system passes efficiency -



BUT! I had to cut a 1/2" off the collectors and modify the cats so that they slip fit / then welded in place. I cut out the Magnaflow 2.5" flange/cut back the heat shield a little to make room for Mig/ Replaced w/ 3" ID.

The O2 bungs expand with heat. In order to keep these from leaking/ use Permatex high heat red w/copper/ lace threads. Remember the O2's are kicked down stream enough to offset heat. Your two white heater wires heat the sensors to about 800 degree's. The Permatex is rated to 1100 degree's/ so it lasts.

Yea, a stock 3 valve can't catch her now - http://picasaweb.google.com/jbrew393...88043316047874 Went from 19 seconds 0-80 to 13 seconds after that exhaust mod. Factory tune @ one quater million miles.

Just saying and bragging ~ everything has to be tight for efficiency to pass when monitor runs. She'll run good as well,- will beat a stock 3 valve, eat Honda's and crap Acura's lol.

 

Bank 1 = cylinders 1-4 passenger side

Bank 2 = cylinders 5-8 drivers side

Easy to remember once you know : )