9N3 GTI Downpipe and Lambda Sensors

[PoloGIT]

Hi all,

VAG-COM tells me the CEL I have is due to error "16414 - Oxygen (Lambda) Sensor B1 S1: Heating Circuit: Malfunction (Open Circuit?) P0030" which from what I've read here and elsewhere is the pre-cat sensor. Before I race off and order one, I just wanted to check that a decat downpipe needs/uses both pre and post cat sensors, as I am considering getting one sometime soon. If only one of the sensors is required, which one is it? Also, if one of the sensors is indeed redundant with a decat, does it need to be written out with a phase 1 / 2 tune or something?

Thanks in advance!

[h100vw]

Hi all,

VAG-COM tells me the CEL I have is due to error "16414 - Oxygen (Lambda) Sensor B1 S1: Heating Circuit: Malfunction (Open Circuit?) P0030" which from what I've read here and elsewhere is the pre-cat sensor. Before I race off and order one, I just wanted to check that a decat downpipe needs/uses both pre and post cat sensors, as I am considering getting one sometime soon. If only one of the sensors is required, which one is it? Also, if one of the sensors is indeed redundant with a decat, does it need to be written out with a phase 1 / 2 tune or something?

Thanks in advance!

The fault code for cat efficiency is written out in our Phase 2 tune.

You need both sensors regardless and the front one is the more critical for running.

Gavin

[seangti]

B1 S1 is the front way as per the research you've done. I've recently replaced the post cat, S2 sensor.

[sambb]

So Gav, the A:F system still actually needs/uses both the pre and post cat sensors - its just that the cat flow error that the second sensor can generate is ignored. Is that right?

[h100vw]

So Gav, the A:F system still actually needs/uses both the pre and post cat sensors - its just that the cat flow error that the second sensor can generate is ignored. Is that right?

I am going on what Kev in the UK has told me. The tune is written to not switch on the CEL, if you look with VCDS the fault is there.

He said, when I asked that it needs to be fitted and working.

Gavin

[sambb]

I'm running a second 02 sensor spacer to avoid the CEL, but I wonder if standing the sensor off like it is could affect mixtures. On the run my car is doing low 12's (AFR that is!) which is ok, but at idle it smells rich since I got the dump/cat/spacer put on. Ever heard of a spacer causing that kind of thing?

[h100vw]

I'm running a second 02 sensor spacer to avoid the CEL, but I wonder if standing the sensor off like it is could affect mixtures. On the run my car is doing low 12's (AFR that is!) which is ok, but at idle it smells rich since I got the dump/cat/spacer put on. Ever heard of a spacer causing that kind of thing?

How are you logging the AFR? The front probe is responsible for mixture regulation as far as I am aware. The rear probe has no influence on things.

Gavin

[sambb]

tailpipe. any idea what afr should be at idle?

[h100vw]

tailpipe. any idea what afr should be at idle?

14.7, you need to look at the measuring blocks.

[sambb]

cool thanks. VCDS cable coming soon.

[PoloGIT]

Thanks guys. So if I install a Milltek decat downpipe (for argument's sake), and am running two healthy sensors with standard or CC phase 1, can I expect to have a CEL due to cat efficiency issues? Depending on who you speak to here in NZ, a CEL can mean you fail the warrant of fitness for road worthiness I'll check that though.

Cheers

[h100vw]

Thanks guys. So if I install a Milltek decat downpipe (for argument's sake), and am running two healthy sensors with standard or CC phase 1, can I expect to have a CEL due to cat efficiency issues? Depending on who you speak to here in NZ, a CEL can mean you fail the warrant of fitness for road worthiness I'll check that though.

Cheers

If you do the downpipe, you want Phase 2 to make the most of it. The cat wouldn't be the restriction if you got one with a cat fitted. The std exhaust would be the choke point.

A 200cell cat will stop the light coming up anyway, most likely.

No idea about the ins and outs of road worthiness in NZ but tbh there's no need to run catless or have the light on.

Gavin

[PoloGIT]

Thanks Gavin, I didn't realise the Cat could be that efficient. The additional NZ$500 for the Cat version of a Milltek is probably the choke point for me though, unless you've got some other suggestions? I guess the other question is how noisy is a de cat pipe going to be? Now that I'm "middle aged," I don't particularly want to be blaring around like a bogan when shuffling from A to B! I'm already surprised at how relatively serious the standard exhaust is, although maybe that's something to do with the 220k it's done...

[h100vw]

Thanks Gavin, I didn't realise the Cat could be that efficient. The additional NZ$500 for the Cat version of a Milltek is probably the choke point for me though, unless you've got some other suggestions? I guess the other question is how noisy is a de cat pipe going to be? Now that I'm "middle aged," I don't particularly want to be blaring around like a bogan when shuffling from A to B! I'm already surprised at how relatively serious the standard exhaust is, although maybe that's something to do with the 220k it's done...

No exhaust shops nearby that can make you a downpipe? Downpipe Hosenrohr 63 5mm Polo 9N 1 8T GTI Seat Ibiza Cupra FR 1 8T | eBay

[PoloGIT]

Downpipe Hosenrohr 63 5mm Polo 9N 1 8T GTI Seat Ibiza Cupra FR 1 8T | eBay

That was looking like a great deal - minus the 19% VAT and only 42 Euros to send to NZ - but then they informed me it's a decat pipe Another 169 Euros for the sports cat, which I guess is still pretty good and it's probably what I'll get when I've got the funds. Will have a look locally at what the options are for a custom pipe.

Cheers