i have a 2005 audi a3 2.0TDI, usually it drives great and gains speed quickly when i floor it but if im on a long drive and i come off the motorway and hit a red light, when i go back onto the motorway and put my foot down it struggles to get past 40, taking my foot off the gas and then slowly accelerating i can get up to 60 but verry slowly, the rpms seem to stay very low. turning the car off, waiting a couple minuets and then going again will fix the issue temporarily untill i go fast again and slow down then go fast again, but sometimes it does not go back into what i believe is "limp mode" at all, its very random sometimes, i assumed i needed my oil change as it was overdue from the last owner, i changed the oil filter and oil and it was fine for a week but it started again today, it ran perfectly yesterday on the motorway for 2 hours, any advice would be greatly appreciated, the car has no warning lights at all when this happens.

I'd recommend a diagnostic check to see if any fault codes flag up. 

Limp mode would come with an engine management light. 

It could be an issue with the turbo 

1 hour ago, Steve Q said:

I'd recommend a diagnostic check to see if any fault codes flag up. 

Limp mode would come with an engine management light. 

It could be an issue with the turbo 

Thank you for the response, it does feel like a turbo issue im going to get a diagnostic test tomorrow then, maybe run some turbo cleaner through it.

It might just be one of the boost pipes leaking or split. Check where it joins up as they can flex here when under pressure 

1 hour ago, Steve Q said:

It might just be one of the boost pipes leaking or split. Check where it joins up as they can flex here when under pressure 

i will check them in the morning, thank you for your help

No probs at all please keep us posted on how you get on 

On 11/25/2024 at 5:21 AM, Steve Q said:

No probs at all please keep us posted on how you get on 

i have diagnosed the car today and only one fault and its "P0234 Turbocharger (TC), engine boost condition - limit exceeded TC Engine Overboost Condition" im going to change the boost pressure sensor and take out the turbo and give it a good clean too make sure its all clear and check that ll the parts look good, will keep updated

Nice one, at least we're in the right track. So either turbo or the sensor. Dhd you check the boost pipes?