P0420

[Dev]

  It might be the composition of the solder being used as to why it did not work for you. I have some free time and have three Denso 02 sensors. I will see if there is something about the Denso wires that doesn't take to solder. 

[Dev]

My old Denso 02 has no issues taking to solder.

On the fist picture you can see the kind of crimp connector that comes with the Denso kit. Probably one of the best crimp connectors I have used for wiring that I bought something similar for other general purpose wiring. The heat shrink  they give you are also quality.

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 I stripped the wires on one blue wire and one white wire and twisted them together. The wires were plenty stiff and accepted  solder without any issues and I tried to pull the wires apart to test the strength, the joint is strong.

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 The solder I use is pretty good being lead free with good wetting properties.

 However you should never solder your 02 sensor wires or any wires used for automotive use especially in high heat areas like the engine bay. Use high quality crimp connectors and heat shrink tubing to give the joint some relief.


 
 

 

[SV-3]

Anyone else have strain relief/supports going to their sensor wires?

[Dev]

Anyone else have strain relief/supports going to their sensor wires?

 I add a few zip ties along the path for strain relief particularly for the the long 02 sensor running from my cat to the connector at the dipstick tube for my 2ZZ. The OEM uses those gray push in grommets along the path but they often go bad with heat and age. 

[SV-3]

Anyone else have strain relief/supports going to their sensor wires?

 I add a few zip ties along the path for strain relief particularly for the the long 02 sensor running from my cat to the connector at the dipstick tube for my 2ZZ. The OEM uses those gray push in grommets along the path but they often go bad with heat and age. 

The ones I have appear OEM?
They are a sort of rigid wire and attach to the 'unused' holes left and right of the engine cam cover.

[Dev]

Anyone else have strain relief/supports going to their sensor wires?

 I add a few zip ties along the path for strain relief particularly for the the long 02 sensor running from my cat to the connector at the dipstick tube for my 2ZZ. The OEM uses those gray push in grommets along the path but they often go bad with heat and age. 

The ones I have appear OEM?
They are a sort of rigid wire and attach to the 'unused' holes left and right of the engine cam cover.

They probably are. I know the one behind what would be your passenger side tail light uses a grommet that goes up and over to give it relief and that is why the length of the 02 wires are long.   As long as you have enough slack and no tension points I think it should be just fine. Those sensor wires are very strong.

[McSmallface]

Do the new sensors come with the aforementioned clips as all the ones on my current one are broken or hanging off

[Dev]

If it's vehicle specific they do from the best of recollection or the actual OEM part. If it's the universal they don't. You can use very small clear or gray zip ties as they do good job and are easy.

[McSmallface]

So the DOX-0206 just turned up and it does indeed have all the clips attached to the wire.

One question though, what type of grease do I use for the thread of the sensor? There is a little diagram in the box saying to grease the thread but the diagram only shows a tube labelled 'denso'.

[Gaz mr-s]

I've known someone who has tried soldering the wires on a Denso O2sensor: Me!

It doesn't work.

+1 ...... was right baffled at the time....

[Joesson]

So the DOX-0206 just turned up and it does indeed have all the clips attached to the wire.

One question though, what type of grease do I use for the thread of the sensor? There is a little diagram in the box saying to grease the thread but the diagram only shows a tube labelled 'denso'.

Copaslip, a very sparing  amount on the male thread of the sensor.

[Dev]

 

So the DOX-0206 just turned up and it does indeed have all the clips attached to the wire.

One question though, what type of grease do I use for the thread of the sensor? There is a little diagram in the box saying to grease the thread but the diagram only shows a tube labelled 'denso'.

 You use anti seize on the threads as Joesson pointed out sparingly but your kit should have included a tube.
 This is so when it comes time to remove its a little easier but that wasn't the case with what I dealt with last weekend helping a local member remove his which was only installed about a year ago where the owner said he used plenty of anti seize. It was so bad that even a torch didn't work and my impact gun was jamming the the 02 sensor tool and stripping the bolt. It had to be taken to a local mechanic with a lift and was an hours work with an acetylene torch.

 What I am going to say next will probably be highly debatable but I will say it anyway because it is relevant. The 02 sensor post cat is different than the ones on the header even though you can substitute the one on the header which is what many owners have done including myself without any issue.
 
What is different about it visually is the body of the 02 sensor has a thicker bolt. This is probably done for more grabbing power because Toyota knows this needs to be heavy duty for removal. It could also be that the way it threads in and locks has enough of a tapered gap to make it easier to be undone but that is just a guess.
   This is one of those instances where the devil is in the details and there is a rational for everything.

[McSmallface]

Well you're not wrong about it being a nightmare, the cat has only just been replaced a couple of months ago so the sensor must have been removed but I can't get it out for the life of me, I sprayed it with WD40 a couple of hours ago and I've heated it til it's glowing and using a proper socket but the fecking thing won't budge ...

It doesn't help that no matter what socket/extension combo you use you just simply can't get my leverage due to stuff being in the way.

[Carolyn]

Get the car up on Jack stands, as high as you can.  If you have access to an angle-grinder, cut the end off the sensor, so a normal six-point socket can fit over it.  Heat with a blowtorch and then use a breaker bar.

That's pretty much what you've done, I guess, but getting the car high enough should allow for a breaker bar?

I've done it this sway a couple of times.

Failing that, it will be: Get the cat off the car and attack it on the bench.

They really can be a bugger.

[McSmallface]

Get the car up on Jack stands, as high as you can.  If you have access to an angle-grinder, cut the end off the sensor, so a normal six-point socket can fit over it.  Heat with a blowtorch and then use a breaker bar.

That's pretty much what you've done, I guess, but getting the car high enough should allow for a breaker bar?

I've done it this sway a couple of times.

Failing that, it will be: Get the cat off the car and attack it on the bench.

They really can be a bugger.

It's off!, I ended up taking the shroud that's above it off from inside the engine bay then cut the sensor off and put a normal socket on it with a scaffold pole on it out the top of the car then torched the hell out of it and gave it some welly and it finally went!

Then came back on here and found that's exactly what you were suggesting!

[Chilli Girl]

Carolyn's advice is always right.

[Carolyn]

Carolyn's advice is always right.

Not always....

[McSmallface]

All back together now so I'm going to take it for a nice long run and see if we get any more codes thrown up. Cheers for all the assistance ladies and gents it's much appreciated!

[McSmallface]

So took her out for over an hour and no repeat code so I feel pretty safe in saying that the issue has been rectified.

Also on a side note the Denso (DOX-0206) came pre greasey up so didn't require any additional lubrication (it was a sticky grey coloured grease)

[shnazzle]

Was just reading the posts and was going to write that the densos come pre-greased. But you beat me to it.
I do add a bit more to the cat sensor. For reasons you now know

[McSmallface]

Ok so took it for a longer drive this morning and I now have 3 codes 🤣.

The original P0420 and P0172 and P0175 (which is bank 1 and 2 running too rich).

MAF sensor clean?

[Dev]

Ok so took it for a longer drive this morning and I now have 3 codes 🤣.

The original P0420 and P0172 and P0175 (which is bank 1 and 2 running too rich).

MAF sensor clean?

 Check your air filter and any constrictions  in the intake system first.

 Your P0420 is probably a genuine cat below efficiency which means that it could be restricted causing the system to have a constriction, this can make the car run rich.  You will be looking at a new catalytic converter.

[McSmallface]

The cat and post cat O2 sensor are both brand new.

[Carolyn]

You're on the right track with cleaning the MAF, I think.  Take the O ring off before you spray it - they swell up and go floppy with stuff like carb cleaner.

It is also worth taking a peek at the air filter.

[Dev]

The cat and post cat O2 sensor are both brand new.

From my experience a P0420 is 90% always a cat below efficiency which means its not doing its job usually because of a constriction  if it is the OEM ceramic cat or something up steam causing a rich condition. A constriction  along the path of the air intake to the end of the exhaust can cause the engine to run rich. Less air for the amount of fuel being injected which causes the ECU to pull fuel.

You can clean your MAF or even replace it as a process of elimination but generally the MAF never gets so bad to cause this condition but anything is possible. 

The other thing that can cause a rich condition is if you have a faulty fuel regulator and to diagnosis it you will have to have the pressure tested. Usually this is unlikely but it can trip the codes you are getting.