One of the oldest ones in the (electronic vw) book... I'm having o2 sensor problems. I have done a search in this category for any previous threads but there isnt too much out there.

Long story short, I replaced my old o2 sensor (according to vagcom wasn't cycling between 0.2-0.9v within 1 second as it should be) with new ebay jobby in an attempt to improve fuel economy and what I believed to be slightly sluggish performance.

Ran about the same for a week or two but then went to ****. I have since had codes thrown left right a centre and couldn't get under 10L/100KM during a 400km road trip. Used to get about 8.4/ 100 on the old sensor (still isn't great).

The codes I have gotten are:

1) 00525 - o2 sensor intermittent signal
2) 00525 - o2 sensor short to ground
3) 00525 - o2 sensor implausible signal
4) 00525 - o2 sensor no signal

What is interesting is that when I plug in the Vagcom and check the lambda voltage on the new sensor, I am getting a fairly constant reading of about 0.345v (+- 0.005v). However, when I probe the actual harness connector in the engine bay, I get 0.66v absolutely constant. Why would it:

a) stay constant
b) read differently on Vagcom and the multimeter?

I must admit that I haven't checked wires but the old o2 sensor did still cycle, albeit it very slow. So am I just looking at a faulty ebay sensor? I thought this at first but others have had the exactly the same experience:

Bentley Publishers - Technical Discussions : Vr6 golf 00525 error code ...

If anyone has had any experience with this itd be greatly appreciated. Any continuity checks between the o2 plug and ECU would be a great help as well.

I have purchase a new legit o2 sensor here in oz but jsut dont want to put it in and find that the car is somehow frying them...

Cheers!
Max