# OBD2 code P0431, warmup cat below threshold



## 9elf (May 19, 2011)

Have this code for bank #2. Car is 2002, 150K, owned since new, well maintained. Internet search comes up with this suggestion: unscrew the oxygen sensor and screw in a sparkplug non-fouler into the cat; then screw oxygen sensor back in. 

1. Has anyone tried this with any success? 
2. Will this cause any issues for timing or fuel injection? I will try this but the non-fouler must first be drilled out so the oxy sensor can fit. I need to order proper size drill bit first. 
3. What is the cause for this code? 
4. What is proper fix?


----------



## Slimjimmn (Apr 8, 2006)

If you can have the software level checked, there is a computer update at the dealer for that code. 
But yes, you can install a O2 sensor spacer and call it a day. 
VW accidentally programmed the incorrect ratios for a faulty catalytic converter into the ECM causing the code to come on even though the cat has not failed. I have been driving 3 years with that code, no changes in MPG or performance.


----------



## RabbitGTDguy (Jul 9, 2002)

Just picked up a 2000 with te 30v 2.8 and I am having the same problem. However, it lists both cats and the funny thing is cats are newer, as are the o2 sensors... 

So, for the software...will VW still honor the TSB? 

If not and I use the foulers...are they installed in the precat bank or post? 

Joe


----------



## Slimjimmn (Apr 8, 2006)

you have to pay for them to reflash the ecm. They should still have the disks (even though from 2003). 
It is only applicable for a few engine control modules from 99-02 2.8


----------

