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Golf r underboost code


Silverbackk

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Recently bought a mk7 r and I keep getting an underboost code come up. The car had a new is38 turbo prior to me getting it. After collecting it I plugged it in and noticed the code (was turning down soundakator) Anyway it went back to the dealership to have this fixed and they found a split vacuum hose which got replaced and had the car back a few days ago. Plugged it in again tonight and the code is back. IMG_1731.thumb.png.fec2edaf91d67eaea5bdec81c34ae293.png

Any idea as to what this could be? Slightly concerned as my 30 day rejection period is up this week and the dealership is slow to get things done. The car was In there nearly two weeks for the vacuum hose and a couple other minor things.
 

For reference it’s a 2015 dsg on 47k miles.

 

Any help/advice would be much appreciated. TIA.

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12 hours ago, Silverbackk said:

Recently bought a mk7 r and I keep getting an underboost code come up. The car had a new is38 turbo prior to me getting it. After collecting it I plugged it in and noticed the code (was turning down soundakator) Anyway it went back to the dealership to have this fixed and they found a split vacuum hose which got replaced and had the car back a few days ago. Plugged it in again tonight and the code is back. IMG_1731.thumb.png.fec2edaf91d67eaea5bdec81c34ae293.png

Any idea as to what this could be? Slightly concerned as my 30 day rejection period is up this week and the dealership is slow to get things done. The car was In there nearly two weeks for the vacuum hose and a couple other minor things.
 

For reference it’s a 2015 dsg on 47k miles.

 

Any help/advice would be much appreciated. TIA.

Could be a number of things from incorrectly set or failing actuator to failing wastegate inside turbo, which usually means turbo replacement. Or even simply boost pipes leaking = do you hear hissing?

 

You need to notify the dealer of the fault and put them on notice that you require it fixed (if that's what you want).  If you don't trust them to resolve it, then you need to invoke your 30day return before it passes to keep things as simple and straight forward as possible and avoid later arguments about right to return... it may still be possible if they fail to correctly repair it, raised inside 30 days, but would be less clear cut. 

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6 hours ago, fastandy said:

Could be a number of things from incorrectly set or failing actuator to failing wastegate inside turbo, which usually means turbo replacement. Or even simply boost pipes leaking = do you hear hissing?

 

You need to notify the dealer of the fault and put them on notice that you require it fixed (if that's what you want).  If you don't trust them to resolve it, then you need to invoke your 30day return before it passes to keep things as simple and straight forward as possible and avoid later arguments about right to return... it may still be possible if they fail to correctly repair it, raised inside 30 days, but would be less clear cut. 


The turbo was originally replaced due to a faulty actuator. They basically said they didn’t want to mess around so just went ahead and replaced the whole turbo for a new one. Can’t hear anything unusual no. 
 

I spoke to them today and they have agreed for me to take it to my local vw dealership for diagnostic and repair and they will pay the bill. They said worse case if it is anything really bad they will refund me in full as it is an ongoing problem that was raised straight away.
 

I’m wondering if it mapped and that’s what’s causing it. I read somewhere of people having this issue on mapped cars because it’s driving fine etc but I haven’t driven another one so it’s hard to tell. I guess I’ll find out this week exactly what it is once it’s been to vw.

 

 

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51 minutes ago, Silverbackk said:


The turbo was originally replaced due to a faulty actuator. They basically said they didn’t want to mess around so just went ahead and replaced the whole turbo for a new one. Can’t hear anything unusual no. 
 

I spoke to them today and they have agreed for me to take it to my local vw dealership for diagnostic and repair and they will pay the bill. They said worse case if it is anything really bad they will refund me in full as it is an ongoing problem that was raised straight away.
 

I’m wondering if it mapped and that’s what’s causing it. I read somewhere of people having this issue on mapped cars because it’s driving fine etc but I haven’t driven another one so it’s hard to tell. I guess I’ll find out this week exactly what it is once it’s been to vw.

 

 

A new turbo should of been tested and set up already including the actuator as bought and installed. But I guess its possible that the actuator wasn't set up right at manufacture and needs calibrating.  There is a voltage range it needs to be in resting state. Although, I would of thought that might trigger a different fault as well.. 

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54 minutes ago, fastandy said:

A new turbo should have been tested and set up already including the actuator as bought and installed. But I guess its possible that the actuator wasn't set up right at manufacture and needs calibrating.  There is a voltage range it needs to be in resting state. Although, I would of thought that might trigger a different fault as well.. 

yeah maybe. I’m hoping it’s something simple as the car seems like a really good example apart from this. There is another fault code showing “control module coded incorrectly” Didn’t think it would have anything to do with an underboost fault? 

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1 hour ago, Silverbackk said:

yeah maybe. I’m hoping it’s something simple as the car seems like a really good example apart from this. There is another fault code showing “control module coded incorrectly” Didn’t think it would have anything to do with an underboost fault? 

Which control module? 

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  • 2 weeks later...

Thought I’d update this post in case anyone come across it.

 

so the car went into vw for diagnostics. They confirmed the code was showing up and basically done a software update and some coding. Copied and pasted below of the report.

ATTEND TO BOOST FAULT IN MEMORY AND CUSTOMER PREVIOUSLY HAD TURBO REPAIR. CONFIRMED FAULT IN MEMORY AND FOUND OTHER FAULT WITH EVAP. REQUIRES PURGE SOFTWARE UPDATE. FOUNDOTHER FAULT CODE RELATED TO INCORRECT CODING FOR THE CONTROL UNIT. CODED CONTROL UNIT AND AND TEST DRIVEN. FOC TEST DRIVEN ALL OKAY WITH NO DRIVING ERROR OR WARNINGS. RE-RAN GUIDED FAULT FINDING AND NO FAULT NO LONGER STORED.

 

Thought it was fixed then plugged it in a couple days later and the code was back. Went back into vw for further investigation. They noticed some sort of silicone around the exhaust manifold so started to dig further. They found a forge aftermarket intercooler apparently fitted in the wrong place and then looked to see if it had been remapped (this was the first thing I suggested). Confirmed it had been remapped back in 2018 and that it is likely that the remap is causing the code. 
 

spoke to the dealership I purchased from and have agreed to return the car for a full refund. It was sold to me as completely stock car and both vw and the dealership agreed it’s going to cost a fair bit to put it right. Let alone the extra wear this potentially bad remap has caused. (Probably why turbo had to be replaced fairly early on).


pretty gutted to be honest as the car seemed like a good car and had good spec vw even said themselves on the first visit they’d bite my hand off for it. But there’s plenty of others out there so currently looking for another one or an s3. 


 

 

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2 hours ago, Silverbackk said:

Thought I’d update this post in case anyone come across it.

 

so the car went into vw for diagnostics. They confirmed the code was showing up and basically done a software update and some coding. Copied and pasted below of the report.

ATTEND TO BOOST FAULT IN MEMORY AND CUSTOMER PREVIOUSLY HAD TURBO REPAIR. CONFIRMED FAULT IN MEMORY AND FOUND OTHER FAULT WITH EVAP. REQUIRES PURGE SOFTWARE UPDATE. FOUNDOTHER FAULT CODE RELATED TO INCORRECT CODING FOR THE CONTROL UNIT. CODED CONTROL UNIT AND AND TEST DRIVEN. FOC TEST DRIVEN ALL OKAY WITH NO DRIVING ERROR OR WARNINGS. RE-RAN GUIDED FAULT FINDING AND NO FAULT NO LONGER STORED.

 

Thought it was fixed then plugged it in a couple days later and the code was back. Went back into vw for further investigation. They noticed some sort of silicone around the exhaust manifold so started to dig further. They found a forge aftermarket intercooler apparently fitted in the wrong place and then looked to see if it had been remapped (this was the first thing I suggested). Confirmed it had been remapped back in 2018 and that it is likely that the remap is causing the code. 
 

spoke to the dealership I purchased from and have agreed to return the car for a full refund. It was sold to me as completely stock car and both vw and the dealership agreed it’s going to cost a fair bit to put it right. Let alone the extra wear this potentially bad remap has caused. (Probably why turbo had to be replaced fairly early on).


pretty gutted to be honest as the car seemed like a good car and had good spec vw even said themselves on the first visit they’d bite my hand off for it. But there’s plenty of others out there so currently looking for another one or an s3. 


 

 

Such a shame and makes me angry 😡 when this happens as they are great cars 😢 when I bought mine second hand from Vw I made them go into what system they can check to make sure it was not re mapped and prove it to me,

they weren’t happy and thought I was going over the top. But when the salesman saw me pick my keys up to walk away they soon changed their minds. Good luck with your search but don’t let this put you off getting another Golf R as there are plenty of straight stunners out there 👍

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Yes, bad luck but good follow up and ending resolution for you, if disappointing. 

 

It is an ever present risk with a used performance car as to history; modifications, how it’s been driven.

 

Even checking for remaps and modifications - most can be returned to stock, so it’s not a perfect science even with a specialist review.  But there are bound to be good cars out there. It’s useful in a way you identified this at such an early stage with the fault code persisting… 

 

Good luck with the looking. 

 

 

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On 23/02/2024 at 16:29, Swerve said:

Such a shame and makes me angry 😡 when this happens as they are great cars 😢 when I bought mine second hand from Vw I made them go into what system they can check to make sure it was not re mapped and prove it to me,

they weren’t happy and thought I was going over the top. But when the salesman saw me pick my keys up to walk away they soon changed their minds. Good luck with your search but don’t let this put you off getting another Golf R as there are plenty of straight stunners out there 👍

Yeah I think there’s probably a lot of mapped ones out there. It’s funny because both me and vw didn’t think it was mapped judging by how it drove. My local vw are looking for a car for me so I’ll ask them to do the same😂 I said I’ll be being my code reader this time and they said we don’t blame you 😂

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14 hours ago, fastandy said:

Yes, bad luck but good follow up and ending resolution for you, if disappointing. 

 

It is an ever present risk with a used performance car as to history; modifications, how it’s been driven.

 

Even checking for remaps and modifications - most can be returned to stock, so it’s not a perfect science even with a specialist review.  But there are bound to be good cars out there. It’s useful in a way you identified this at such an early stage with the fault code persisting… 

 

Good luck with the looking. 

 

 

Yeah pretty happy to be giving it back to be honest. Vw said they weren’t sure what else they’d find and it’s already in the thousands judging by what they found. 
 

unfortunately it’s hard to know. Like you say they can easily be returned to stock. I think with the next one it will have to have less owners. This one had 5 owners and I originally thought it’s not too bad being the sort of car it is, service history was excellent (including haldex and dsg) but thinking of it having more owners does increase the chances that one of them has tinkered with it. 
 

Absolutely. I did read that a lot of the remaps (particularly mountune) does cause this code. Because the car was driving faultless I did think this was the most likely cause throughout.

 

cheers for your help! And I’m sure I will! 

 

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