Replacing EGT sensor

[AudiNike12]

Is it true that I've to replace them in pairs? Even if I get a used one with exact same numbers?

2.7t

[m_haiser]

I wouldn't get used egts personally I'd just code them out because they're going to die on you again

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[AudiNike12]

Oh ok. How do I code them out? What tools are required?

[m_haiser]

A Ross tech (or similar aftermarket/ebay) cable and some reading and understanding on nefmoto.com

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[AudiNike12]

I've VCDS. Guess I'll start reading and see if I can get it done. Thanks

[Audibot]

x2 on coding them out. They are so prone to failure it's really not worth it. Although if you are handy and precise enough with a soldering iron, you could take a stab at fixing them yourself. Usually the connection to the board is what fails via the repeated heated/cooling cycles.

[m_haiser]

Read carefully, follow all precautions and mentally prepare for the possibility of needing to replace your ecu should something go wrong. I've had it happen, stupid ke didnt correct checksum and bam dead ecu

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[AudiNike12]

I've this code: Exhaust Gas Temp Sensor 2 (G236): Short to Ground

Does this actually do anything? I've not noticed anything wrong with the car. Maybe I can just leave it?

[m_haiser]

Itll put you in limp mode of about 5psi of boost as opposed to the 7-10 it should have and most likely retard timing

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[AudiNike12]

Hmm...Coding it out seems to be a bit of a risk if I'm not careful. And knowing me, I'll screw something up. Had it been the passenger side sensor I would have just replaced it with a used one since it's easy to do and if it would give up I would just replace it again. They're available for $30. The driver side is another story. I don't want to replace that one twice lol

[2.ohhh]

I got the little resisters of of eBay that jumper the plug to fool the ecu. Popped them on and bam, from 5 psi to 18, all is good! Except for emissions if you have to deal with testing...car will run great, but won't pass readiness for any emissions test.

[Calif_Kid]

I got the little resisters of of eBay that jumper the plug to fool the ecu. Popped them on and bam, from 5 psi to 18, all is good! Except for emissions if you have to deal with testing...car will run great, but won't pass readiness for any emissions test.

I've installed a few of the EGT deletes (that get attached to the plugs on the top/right side of the engine) like https://www.ebay.com/itm/Audi-B5-S4-...4AAOSwQsNZzeJF and the readiness sets fine as far as I know. The EGT deletes are small enough, that I doubt that most smog shops would spot them even if they did a visual inspection. If just one of the EGTs is bad, then the EGY delete can be installed for just that one bank, and the other left to run as normal. - Jim

[Kruat]

Read carefully, follow all precautions and mentally prepare for the possibility of needing to replace your ecu should something go wrong. I've had it happen, stupid ke didnt correct checksum and bam dead ecu

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You sound pretty familiar, are you for hire? I'd like to code out egts and sai on my allroad. I have vcds, but never messed with nefmoto.

[AudiNike12]

What exactly is an emission test? I dont' know if we have them here in Sweden. All I see them do during an inspection is to put something in the end pipe and measure something.

And where exactly do I put these EGT deletes?

Edit: Before I order these EGT delete plugs($100 yikes), I'm gonna go out and take the car for a drive and check the boost in VCDS

[AudiNike12]

A bit hard reading the graph but looked like it topped around 7-7.5psi. 1500mbar. Then subtract 1000mbar. But now there was no code present since it's intermittent

So using these plugs, will I pass emission test?

[2.ohhh]

If you are on a sniffer test only, the EGT deletes should not give any problems....they basically just read the EGT (Exhaust Gas Temperature) to double check that you aren't running too lean. If they detect an odd or hot reading, they put the car into limp by withholding boost and adding fuel, effectively killing power, but still very drivable. When mine were going out, it would change on a drive...weak boost at one traffic light and "holy sh*t" at the next...granted, I was on stage 1 with 16 psi on boost...quite a bit of difference from 5-6 psi. If you are not on a tune of some sort, it would be a minimal difference in power...I forget stock boost, but it's not 16-18 psi.

In fact, after thinking a bit, you might have a better emissions sniffer reading with the bypass plugs...IF you are having a code at the time...if it is in limp, then it will give too much fuel for the test. Main issues with the plugs are it won't pass an OBD test for emissions....

[rollerton]

If you are just a normal driver on stock tune you can jump the signal from one to the other; if you have no codes from the working one. I did that on my old S4- a friend of mine still owns the car and it's STILL that way 10 years later. I don't think they do much at all if they're measuring less than about 900* ? Maybe it's hotter than that even... They basically add fuel to cool a hot turbo.
Also both sides are the same exact part, just a different connector so you know which is for which bank. They're totally interchangeable. The average person wouldn't know if they had an EGT going out. The can be useful for aftermarket tuning, but it's sort of a a safety thing to keep temps down when stock. Not sure what the point of coding them out would be. They're cheaper than a tune, super reliable and fairly easy to replace and they DO perform a function that could be SUPER important at some point...

Here's some info from the S4 Wiki that'll learn you up on those things: https://s4wiki.com/wiki/Exhaust_gas_temperature

[AudiNike12]

How do I jump the signal? Do I take a wire from the non working one and tap into the working one. If so, which wire?

[rollerton]

If I remember right: disconnect the bad sensor, jump the BLUE wire from the good sensor still plugged in to the blue wire on the connector (disconnected) to the other sensor harness.
That's it.

[AudiNike12]

What's the best way to jump a wire? Will a scotch lock due? If I remove the blue wire from the connector on the bad sensor and use a scotch lock to tap into the blue wire on the good sensor

[rollerton]

What's the best way to jump a wire? Will a scotch lock due? If I remove the blue wire from the connector on the bad sensor and use a scotch lock to tap into the blue wire on the good sensor

Should work. I think when I did it I just used a butt-splice with 2 wires in one end, 1 out the other? Or solder/ wrap. But it worked to get rid of the error and any problem it might have had that wasn't noticeable. Not ideal, but maybe 1 step better than coding them out completely? And it's free/ reversible. So no harm done.