quattroworld.com Forums: There is a post-cat O2 sensor on the downpipe.

All messages | Search Forums | Return to TT Mk2 + TT RS

There is a post-cat O2 sensor on the downpipe.
Posted by: JohnLZ7W (302) on 2014-03-15 22:03:34 In Reply to: Where is the "first" sniffer? The TT_RS only has the single o2 sensor on the downpipe, or is there posted by NoogMan on 2014-03-15 20:40:46	Share \| Report

The TTRS has it's primary cat right between the turbo and the downturn. That's where the post-cat O2 sensor is. Further down the exhaust are the secondary cats which are not monitored at all and I believe are primarily for cold start emissions.

You can just see the pre-cat O2 sensor here which given the proximity of the cats has to be on the turbo housing. Note that is not a factory downpipe.

Here you can see the primary cat in the downpipe and right at the turn there's the O2 sensor.

The large section towards the middle are the flex pipes and then the secondary cats at the start of the midpipe. That's what lots of folks have removed.

Thread:

Downpipe in, mids in, o2 spacer apparently not working......CEL came on...will it hurt anything? - NoogMan 2014-03-15 20:32:06 (1073 views)
- i put the spacer in the sensor at the beginning of the downpipe and plugged the second - lpriley32 2014-03-17 15:04:54 (1040 views)
- Anyone ever try these mini-cat O2 spacers? - illbill 2014-03-16 14:52:18 (1366 views)
- Second sniffer is ONLY emissions control. Has ZERO effect on the fuel trim. - goTTwo - DEFCONs+ 2014-03-15 20:35:40 (1024 views)
  - Where is the "first" sniffer? The TT_RS only has the single o2 sensor on the downpipe, or is there - NoogMan 2014-03-15 20:40:46 (1025 views)
    - There is a post-cat O2 sensor on the downpipe. - JohnLZ7W 2014-03-15 22:03:34 (1091 views)
      - John, so the sensor on the turbo housing does all the monitoring of air/fuel? And, when I get the  -  NoogMan  2012-01-24 00:10:38 (1045 views)
        
        Is this for an APR tune done by GMP?   -  goTTwo - DEFCONs+  2014-03-17 09:06:43 (1009 views)
        
        Haven't gotten the tune done yet............they are doing an APR stage 2 tomorrow.   -  NoogMan  2014-03-17 09:48:20 (1010 views)
        
        Craig, just let the guys at GMP know you are getting the code and what you did. They will take  -  SevernTTRS  2014-03-16 06:26:46 (1037 views)
        
        I will do that! I just didn't want to hurt the car driving it with the CEL on......I haven't pulled  -  NoogMan  2014-03-16 14:04:53 (1023 views)
        
        Yes it is there. They had a track day Saturday and called to ask if they could trailer it down and  -  SevernTTRS  2014-03-16 16:41:24 (1019 views)
    - After the CATs. That is where the spacers are supposed to go. - goTTwo - DEFCONs+ 2014-03-15 20:44:04 (1024 views)
      - actually, there is only ONE o2 sensor on the RS, it's on the downpipe, but from the engine diagram,  -  NoogMan  2014-03-15 21:02:15 (1057 views)
        
        I am surprised it is on the Pre-CAT and not the actual CATs. All the CEL (ANY CEL) is REQUIRED  -  goTTwo - DEFCONs+  2014-03-15 21:19:59 (1029 views)
        
        Yeah, I took out the 2ndary cats and put in bypass midpipes. I just wanted to make sure I wasn't  -  NoogMan  2014-03-15 21:33:24 (1055 views)

You must be registered and logged in to post. Please select an option:

All messages | Search Forums | Return to TT Mk2 + TT RS

Copyright © VerticalScope Inc. All rights reserved.

quattroworld.com is an independent Audi enthusiast website owned and operated by VerticalScope Inc. Content on quattroworld.com is generated by its users. quattroworld.com is not in any way affiliated with Audi AG.