I heard that using racing fuel will mess up our O2 sensors, even with a chipped program for that type of fuel. Is this true? O2 sensors should be replaced every 100k miles or so normally, so how often should they be replaced if using race fuel for a few races every month or two?

 

Not at all. I raced for many years on a stock 02 sensor using 100-105 octane unleaded fuel. The first 2 years was every single weekend.

 

That's the reassurance I was looking for. Thanks.

 

The lead in race gas (if it's leaded) will kill the cat, not the O2 sensors.

 

I always thought o2 sensors were supposed to last for the life of the vehicle....kinda just assumed...

 

Well 02 sensors are a wear item, even if they are working doesn't mean they are working at 100%.

 

It's time to replace mine anyway. They're both showing up on the check engine light, and they've got 122k miles on them. What kind should I get? I've noticed a huge price difference. I'm kinda' cheap, but I won't sacrifice my Audi's well-being for it, kind of an oxymoron, I know.

 

OEM. You can go with the cheaper wide band sensors which are also made by Bosch and even have Audi/VW part numbers on them, but the problem is they have a much shorter harness then the OEM ones you get from the dealer and thats one of the reasons they cost a little bit more.