Hello

 

I have a "P0420 - Catalyst System, Bank1" error on my Superb 3 DFCA 2.0 TDI, this issue continues since I bought a car on milage ~184000km

I tried Cataclean, LiquiMolly DPF cleaner and no result

 

Interesting thing that it appears only during DPF regeneration(passed successfully) and I can't find any similar problem on another diesel cars (like Passat, Octavia, etc.)

Lambda probe sensors are located on DPF and after, I'm a bit confused what to check?

 

Need some recommendations how to fix/find it

 

Thanks

 

 

Checked both CATs after DPF and on the top of DPF, all good. Have no idea what to check next

The problem is solved. I struggled with it for a year.

In the end, it turned out that the sensors of the exhaust gas temperature were mixed up

 

1. Noticed that Output Gas Temp is higher then Input

 

2. Did some ELSA/ETKA research to find what temp sensors should be installed and what color.

3. Found some photos in internet with temp sensors installed correctly

 

4. This is how they installed in my car. Temp sensor after CAT has different wire color, should be black and vice versa

 

5. Now installed correctly

 

 

 

 

I don't know who needed to remove the temperature sensors. Car was servicing on dealer. I have recorded in service history that ~800km before purchase, they replaced DSG.

 

Edited 12 April, 20242 yr by zacko_O

Hello Zacko I just wanted to tell you that you saved me so much headache! I had this exact issue on my Passat B8.

I recently had a temperature sensor changed (which was another whole headache as it was underneath the turbo so had to take it to a mechanic) and then after I got it back started getting the same issue when regenerating DPF. Did some research on the internet and was getting nowhere until I stumbled across your post!

I compared my pictures from before the sensor changed and after and they were exactly like yours! So I pulled out the trusty 19" spanner and did a quick switcheroo.

Thank you so much. I made an account just so I could reply to you.

Have a great day man.

@donmash I'm glad my experience helped👍