Sam Hill

The first post I made on this forum was about buying a used 2002 TT Quattro Roadster (225hp 6 speed manual) and noticing that the previous owner had installed a BOV.

Being a fan of efficiency and of not causing damage to my car, I replaced it with a forge 007 diverter valve. Almost Instantly my car started to perform better.

I cant shake the feeling though that my car is still sluggish on takeoff.
I have to give what definitely feels like too much gas when starting off in first gear. Usually it takes off sluggishly and then jumps forward after the initial 10 -15 mph as if something just realized what it was supposed to be doing.

I might have misread the situation, but something tells me my o2 sensors my have gotten worn out from that BOV messing with them. So I ordered a new o2 sensor (Bosch 17014 wideband OE fit).

All of the info I could find led me to believe:

1. My car has two o2 sensors: pre cat and post cat

2. The pre cat (up pipe) o2 sensor is the one that regulates air fuel mixture and can cause my mixture to be rich if it isn't working right.

3. The pre cat sensor is located under the car on 180 hp TT and somwhere in the engine bay on the 225 hp TT.


Finally, the issue.
I found what is obviously an o2 sensor in the engine bay of my car pretty conspicuously placed right next to the firewall, threaded into a large metal pipe, facing up, with a wire running to a connector that hides behind some heat shielding. But the connectors aren't the same.

The connector on the car is a slim horseshoe shaped plug with one straight line of 4 prongs. The connector on the new o2 sensor is a wide horseshoe shaped plug with 8 prong inserts.

Car part sites tell me that what appears to the the sensor with the correct plug shape/type is in fact the incorrect sensor for my car.

I though about spicing but the wire coloring on the car and new sensor aren't similar at all, and my go to mechanic told me its not a good idea anyway.

Should I order what I'm told is the wrong sensor?

Should I splice?

Should I pay way to much money at the dealer?

Is the thing that I think is an o2 sensor some kind of phoney concealing the fact that the real pre cat sensor which has the correct plug is hiding under the car somwhere?

Could the sluggish acceleration issue be completely unrelated to the o2 sensor entirely?


I'm not expecting answers to all of those but any info would contribute.

42TT

Sounds like you ordered the front o2 for an AWP.
You must have a ATC (engine code).
Do NOT splice it in place. it will not work.

Check out here - https://www.ecstuning.com/Audi-TT_MK...Oxygen_Sensor/

You should be able to access the first o2 from the engine bay. The rear sensor is pretty far back so you are definitely working with the correct sensor.
Both sensors connect to the main harness in the same spot so just follow the wires the be sure.
Don't buy from the dealer.

I'm not sure this issue sounds o2 related.
I would disconnect the battery for a few minutes and then reconnect to clear any old codes around the BOV.
Also this will reset your fuel trims which will help alot with having the correct DV installed.
Drive normal for 20 miles to let it adapt. Then see if the problem is still there.
If it is check for vacuum leaks everywhere.