I was getting an intermittent P0420 code on my Tiguan, it would go away at first but then became more frequent. At 128,000 miles I was hoping the converter wasn’t toast so I removed the downstream O2 sensor and it looked like this. I replaced it yesterday and so far there is no pending code but the permanent code hasn’t disappeared yet. Is this amount of ash enough to cause a problem?
2020 Tiguan O2 Sensor Ash
- Thread starter kschachn
- Start date
I've had P0420 showing up on our 2010 Nissan Cube w ~140k miles on it. It first popped up shortly after starting the first run of Valvoline R&P and again a couple weeks after a reset. I had added some STP Ultra fuel system cleaner around that time and the code did not return for several months. I'm monitoring oil consumption now during it's 2nd OCI of Valvoline R&P and keeping an eye out for the code.
Nothing conclusive yet but in my experience the P0420 code has been LESS frequent after switching to VRP and using a PEA FSC.
Have you used any fuel cleaners? What is the rate of oil consumption?
No I’ve never really used a fuel cleaner. I could try.
The consumption is variable based on driving style but it’s about 1 quart in 2000 miles, a bit dismal. I tried 5 OCI of Restore and Protect but it didn’t help. I think the valve stem seals need to be replaced and I’m still planning on tackling that this summer.
That looks like melted catalytic converter bits. That looks similar to the remnants of the converter on my F-250 I replaced not long ago, also with a persistent P0420. The code has been gone now for about 500 miles since replacing.
I've seen worse, but yeah, that amount could possibly be causing the code to pop up. Bosch sensor? Any lean codes from the upstream sensor?
Well it’s pretty soft and fuzzy, you can easily wipe it off. It seems like regular ash.
The one in the picture is VW OEM and I replaced it with a Bosch.
So far nothing from the sensor.
