Sorry if this is harsh, but if the diags tells you it has an EGT probe fault, why would you change a lambda probe! :?

A faulty EGT probe will usually tell the ecu the car has high egt's and that will throw out the fueling, the probe needs to be replaced, its not a common fault but does happen so you'll need to source one and get it changed.

http://www.wak-tt.com/egt/egt.htm

 

Hi Wak and thanks for the reply!

I changed the front lambda as I didn't realize the BAM engine had a separate EGT sensor and clearly wrongly assumed it was the front O2 sensor that was the issue as this seemed to be an overfuelling issue and fuel trim is controlled by front lambda

I will source the correct part and see what happens.

Cheers,

Tim

 

Well the EGT will probably be sending a high value triggering protection fuelling hence why its so rich, once its sorted the correct temps and your nice new lambda will hopefully sort the emissions out for you.

no harm in having a fresh lambda probe if the cars done a few miles. Lambda was genuine Audi or Bosch I hope?

If you have vagcom Review Block 112 in measuring blocks.

 

Hi Wak,

Yeah I replaced with a Bosch item....wouldn't do anything less What should I be looking for in block 112 in VAG-COM? From the quick research I have just done the EGT sensor is only available from Audi?? Ouch this is going to hurt me thinks! [smiley=bigcry.gif]

Tim

 

See what value you are seeing from the EGT on block 112, it may of course work when cold but fail after some driving but see what it is and log it , post the values up.

Been a while since I had to buy one but they were around £180 approx.

 

Is it worth having a look to get one second hand or are they like the proverbial rocking horse .......? Or alternatively just a false economy?

Code comes up again instantly I erase it, so suspect it is knackered....or is it possible it is unplugged maybe?

 

The exhaust temperature sensor has a limited range of between 900 and 1000DegC. It only affects full load fuelling. They can fail quite regularly on other VAG products where they are used (everything from S4/RS4 to W12 to Arnage/ContiGT) as they are very installation (read the location of the black box) sensitive.

It *may* affect your fuelling at idle but I doubt it as it has already recognised a fault with the sensor and is therefore ignoring it. This will command extra fuel but it should only happen at full load, not at idle where the MOT test is carried out.

They were originally made by ABB automation for VAG.

If you unplug it, you will get the same code. You own't find one second hand and if you do it's probably dead as well. Also be sure to get the right one as different issue levels have different temperature ranges.

 

Hi RG and thanks for the post.......so are you saying that the EGT sensor is unlikely to cause the high CO at fast idle on the MOT? If not te EGT sensor then what else might it be as this is the only fault code being logged?!?

I have just been to the stealers and purchased an EGT sensor, it has been upsuffixed to 06A 919 529D according to their systems, does this sound correct?

Cheers,

Tim

 

The exhaust temperature sensor has a limited range of between 900 and 1000DegC. .

This is not true on a TT ask anyone using a liquid tt to verify

RS4 and S4 also have a full range on the probes but their diagnostics only show the range from which protection kicks in I.e you will always see 945 until the temps actually exceed 945

Sent from my iPhone using Tapatalk

 

Yep like I said Wak, the ranges vary according to part number. Across a wide range of cars in the VAG range. Thanks for clearing up which part the TT uses!

The early parts were only for high temperature ranges eg early S4/RS6. They did change later but was not sure which model year for TT. If you've read it on a diagnostic for these cars then they changed earlier rather than later. It always did seem a little odd to fit a thermocouple and then only use part of the range.

In any case they are only there to affect full load enrichment so the lower temperature part of the range is not important. The idea being that you save fuel by running lean as long as possible and then only command extra enrichment when needed as determined by the measured temperature. It allows less steady state enrichment in on/off autobahn driving than would otherwise be the case.

 

EGT Protection is not limited to WOT, its depends on engine temps and load, A warm engine and fast Idle test could certainly cause enrichment if the probe were giving out a high value.

In the absence of hands on inspection, data logs and with a clearly defined fault, the egt probe should be changed regardless, but I think that will be the cause of this issue.

If this doesnt fix it then its going to need more extensive logging.

 

Well if we want to be precise about it, it's a load threshold that is mapped as a function of engine speed and inlet air temperature. [smiley=book2.gif]

It doesn't actually matter though as because there has been a fault code stored, the temperature controller defaults to an internal modelled value and ignores the sensor (when P1453 is set).

I've never seen the load threshold calibrated much below the min boost line and certainly never as low as part throttle. That area would solely be in the closed loop operating region and you'd never exceed the EGT limit (to protect the manifold and turbo) at light loads.

 

Thanks for the logged data, If you get the EGT probe done it should sort out your emissions for the MOT.

If you log the same after its changed and send it to me I can advise you further before you do your retest but I'm 99% certain it will be ok.

It doesn't actually matter though as because there has been a fault code stored, the temperature controller defaults to an internal modelled value and ignores the sensor (when P1453 is set).

Sorry but this is wrong in this platform.

Edit:-
Thanks for the updated logs, clearly the enrichment has gone and you should be fine for the MOT now.

When people post with no objectivity or humility in that they may be be wrong, it just turns into a shouting match and I'd rather be trying to help you than argue with someone so up himself he couldnt even for 1 second believe he could be completely wrong.

Had we carried on posting , you would have been lead up the wrong track by this guy, costing you wasted time and money.

Needless to say its his style of attitude in the tuning world that made us get into this ourselves, if we dont know we try to find out and if we know its backed by evidence, if we are theorising its with good foundation and humilty it may be wrong!

 

Hi Wak,

I have changed the EGT sensor and as you suspected it has cured the problem, not the nicest job to do outside in below zero conditions but hey ho needs must

 

Car flew through MOT re-test yesterday on emissions thanks to all your help and advice....especially Wak [smiley=thumbsup.gif]

 

Thanks to this post it has saved me an awful lot of time, possibly wasted money and definitely stress. I have been carrying intermittent EGT sensor fault for ages and again as you failed my MOT today with almost identical readings except for Natural Idle which was CO: 0.392.
I have actually had the sensor changed once and wiring checked though. May be I picked up a faulty replacement!

Cheers

Stuart

 

If you don't mind me asking... What did you pay for the sensor? Cheers Stu

 

Hi Stu,

Hope you're sitting down.......it was 180quid from the 'stealers'

Tim

 

Wow... Thought I'd paid that earlier this year for replacement from Audi... Have called mechanic and he thinks he might be able to return and get another no charge!

Cheers and glad to hear yours is sorted even at £180..

Stu