Volvo 2016 XC90 P0420 code

gavinh

Hi Guys, I hope your all having a good christmas. As title suggest my XC90 T6 keeps on throwing this code, I have replaced both the O2 sensors, also removed the cat to check if it was blocked or cracked and ran a penrite cat cleaner through the system, when I removed the cat I did find the retaing clamp between the cat and turbo was snapped.

Has anyone got any more thoughts of what I can look at before I try a standoff boss for the O2 sensor.

Cheers

Gav

bumperplates

Maybe sparks and plugs if you have replaced/checked everything else?

gavinh

Thanks, the spark plugs were done about 4-5 months ago and replaced the pcv diaphragm shortly after as that failed around the same time. we have had this fault on and off for 6-8 months, it honestly didn't seem to affect the car, it's just annoying. I have read on different forums about the Flexi pipe leaking, but I thought this would affect the down stream more?

One interesting thing though, it sound like a sewing machine, is this normal?

Cheers Gav

bumperplates

Sorry I didn't see this post earlier, and a belated Happy New Year to you.

Hmm, the sewing machine sound is an interesting one. I wonder if it's the engine oil that you was used which isn't providing enough lubrication. I do hear that these engines are almost indestructible so don't think it would be the metal chain inside the engine.

I'm not a mechanic though and making a guess.

gavinh

so this problem is still rearing it's ugly head, I installed a O2 spacer, and it didn't make a difference, actually there wife said the car ran worse and stalled a couple of times.
I've smoke tested from the tail piple up to the intake, I found a small leak leak at the joint of the Flexi pipe, which I fixed and there looked to be a small leak at the turbo to manifold.
I've checked the parts and their doesn't seem to be an gaskets etc between the manifold and turbo??

timbo

gavinh

Which 02 sensor did you space?

Usually a 90 degree spacer on the rear 02 works fine.

I used to do this lots of the n/a versions

gavinh

I used a 90 degree on on the front drivers side, I assumed this one was the one related to the P0420 fault? I'm using Vdash for the interface with the car.
would the rear pass side one not be hard to do?
Cheers
Gav

timbo

gavinh there isn't much room up there, but I would always space both rear sensors. If you spaced the front sensor it would have upset the fuel mixtures. The rear 02 sensors monitor cat convertor efficiency

Some of the later ecus might be hard to trick as they want to see some fluctuations. Does the live data tell you much?

Something like this with a mini cat may help? You can also clock it in any direction

https://www.ebay.com.au/itm/354483691504?mkcid=16&mkevt=1&mkrid=705-154756-20017-0&ssspo=gkmfntt6qne&sssrc=4429486&ssuid=RDozT-dlTGu&var=&widget_ver=artemis&media=COPY

bumperplates

I thought the rear would be easier than the front, at least on the V8.

gavinh

@timbo,
that's the one I used initially, I removed the mini cat after the wife said it was stalling, but happy to try it again on the other 02

timbo

Before diving back in I would check the live data after it's been running for a bit and compare the readings for the 2 rear 02 sensors and see if they're the same