2007 SR5 5.7L gas V8 P0420

P0420! My arch nemesis! Cleared the Bank 2 code with a new O2 sensor, Bank 1 persists. No power loss, no noticeable change in fuel consumption, no apparent exhaust leak (except for a minor one on the Bank 2 side).

So, I switched O2 sensors figuring that the code would change to Bank 2 indicating a bad O2 sensor. Nope. Watched a few videos on testing the cable running to the EFM but I'm not as confident as I'd like to be with deciphering the info and executing the testing. With the truck running I tested voltage across the O2 heater wires and apologies, but even while starting this i felt confident of the info but I now doubt myself, I got no reading so I tested from heater positive to ground on the engine block and got something like 5V. Ultimately I realize it could be the cat after 220,000 miles but I've had trucks with blocked or failed cats and I'm just not seeing those issues.

Does anyone have any definitive test numbers for the 4 wires running from O2 Bank 1 Sensor 1 to the EFM? All of the results from searching have come up with different wires than I have so that throws me off too. Mine are;
Green - signal (as I understand it)
Green/Black stripe (Volt reference)
Purple - Heater positive (aiui)
Purple/white stripe Heater ground

2007 Tundra SR5
Double cab
5.7L Gas V8

 

First post needs a hearty welcome... Hearty Welcome and congrats on the Rig. Any pics?

 

I've been digging but the profile pic is the only one I've found so far. The truck I had before this was a Nissan SE with the splashed paint decals on the side. Absolutely loved it for traveling but living up north apparently took it's toll. After I got a company vehicle the truck sat for at least a year except for when my son, too young to drive on the road yet, would drive it to a local swimming hole out in the mountains. When he got his license he asked if he could get it legal again to use which was ok by me. Him and a friend started jacking it up to put on new tires but when they started lifting the rear, only the box went up. The frame had rusted through in a 6 year old truck. Contacted Nissan since they had a lifetime rust warranty but they weren't honoring it. Forum after forum I saw the same issue. Then I happened on a Toyota forum and it seems the steel then was sub par and had issues so Toyota made things right for their owners. Boom! Toyota fan lol.

I still love the style and body shape of the Tundras. I have had at least 7 people offer to buy it in the last few years and I'm kind of stuck on it. Don't need the 4 wheel drive down here in NC as much as I did up in the PA snow belt, (I have a house in a small town just above Centralia, the mine fire town which is where my wife grew up. Western edge of the Pocono snow belt), but pulling the boat out of the water and running my trailer for DJ/KJ shows in yards and fields it helps. Next one tho will have the Bronze Mica paint on it =). Thanks for letting me rant hehe.

 

If you monitor live data, what do the two traces look like for the downstream O2 sensors on each side?

How are your misfire counters?

What's your long term and short term fuel trim?

You would want to get the live data going for both O2 sensors with the truck going, then start pumping the brakes like crazy. That should lean out the engine hard and that should be pretty quickly and clearly picked up by those sensors.

You are thinking clearly in terms of not paying for new catalytic converters. More diagnosis is required to know what's actually wrong.

 

you have a bad cat on bank 1 cat is no longer efficent

 

That is one of many possibilities, and certainly one of the most expensive ones.

 

Thanks audiowize. I'll put the scan tool on it and get that info. When you say that after pumping the brakes it should be picked up by the sensors, what kind of numbers should I see?

 

You would expect both O2 sensor graphs to take an absolute nose dive.

 

+1

 

I am enjoying how many people want you to throw a pile of money in for new cats without knowing if that's the actual issue.

Of interest would also be where you picked up your reacement O2 sensor. If you got the cheapest one at the local autoparts store, that would likely make its own issues as well.

 

@audiowize , sorry that it's taken this long for the info. Been putting out fires. The only thing I didn't get was misfire count since I didn't see an option to enter $6 mode on my scanner but I've never had a P030X code.
Based on 700-800 rpm -------------
Short term Fuel trim 1 -0.800 -
Long term FT 1 - 6.3 -
Short term FT 2 - 0.0
Long term FT 2 - 5.5
Short term FT 12 - 99.2
Short term FT 22 - 99.2

While pumping brakes
SHRT FT 1 - 8.6
LongT FT 1 - 2.8
SHRT FT 2 - 11.7
LongT FT 2 - 24.2

CAT temp 11 - 416
" " 21 - 416
" " 12 - 332
" " 22 - 332
How are your misfire counters?

What's your long term and short term fuel trim?

You would want to get the live data going for both O2 sensors with the truck going, then start pumping the brakes like crazy. That should lean out the engine hard and that should be pretty quickly and clearly picked up by those sensors.

 

You might need a slightly nicer scan tool, maybe something like this:

$28 Autel Professional OBD2 Scanner AL319 Code Reader, Enhanced Check and Reset Engine Fault Code, Live Data, Freeze Frame, CAN Car Diagnostic Scan Tools for All OBDII Vehicles After 1996, 2025 Upgraded

https://www.amazon.com/Autel-AutoLi...d=1636123079&sr=8-3-spons&smid=A3MNQOSQ336D3K

A short term fuel trim will jump around all over the place and a long term fuel trim will just sit there and not really move.

 

My 2007 had P0420 & P0430. Mine was fairly easily diagnosed though, as I heard the cats rattling lol. Expensive indeed, but I went with magnaflow direct replacement cats which is new front pipes with cats. Bolt on replacement. Was about $1000 for both sides altogether and worked fine, CEL never came on. Ran them for a year before i went with ARH long tube headers with their catted front pipes. If you end up needing to replace the cats, I cut you a deal on mine, only used for 14 months lol.

 

Thanks Trust86. I’ll let you know.
i understand what you’re saying about the short term audiowize and they were. I basically put the average readings. Having the same brand in the

$48 AL329 OBD2 Scanner, Upgrade of AL319 & MS309 Code Reader, OBDII Reader with Auto VIN, Live Data, DTC Lookup, Emission Monitor Test, I/M Readiness Smog Check CAN Diagnostic Scan Tool

AL329 which I haven’t updated in a minute I wonder if it has anything new

 

Thanks Trust86. I’ll let you know.