Hello! 

First time poster but hoping for some help with a fault currently being experienced with my Audi Q5 2.0 TDI (2016), which my garage seems puzzled by! 

 

A few months ago I started experiencing engine warning light and flashing coil light and car going into limp mode. The error codes at the time were: 

P048e exhaust pressure control valve signial circuit is high 

P047f exhaust pressure control valve 'A' stuck open 

P0299 turbo not receiving correct pressure. 

 

Took to garage, who replaced boost pressure sensor, but issue returned. 

I have checked glow plugs, and air intake / filters, all fine. 

Took back to garage, who checked the wiring to the sensor and have found one wire is putting out 5v rather than 1.5v. They tried to trace the issue and said it traced bac to the ECU. 

I have cloned & replaced the ECU but issue returned. 

Took back to garage, who have said the valve is now just actuating constantly. This presents as a loss of acceleration power in the car, I think it is constantly in limp mode. It also seems like it is running much hotter, with heat noticeable when stepping out of drivers side. Also seems like a fan continues to run post-switch off...

 

The same fault codes continue to return after clearing, and if the valve is mechanically fine with no wiring damage and no ECU issues I am at a loss as to what is causing this.. #

 

Current thoughts are: 

1) Garage has maybe missed some wiring damage that could be causing the wiring to output a higher voltage? It has been checked twice though so would be unlikely but possible. 

2) Buy a VCDS tool and code out the valve entirely and mechanically fix it in the open position. Not ideal as affects performance, DPF regen etc. 

Any suggestions, next steps etc appreciated as the next appointment with Audi is in a months time and ideally wouldn't be waiting that long. 

Thanks! 

 

Edited July 29, 2025Jul 29 by pmyjf2

Joe.

Has the car been modified in any way? Re-mapped, DPF deletion, EGR deletion, for example.

Hi, no modifications other than a replacement / cloned ECU (was a plug & play job) 

 

thanks 

joe 

Well that rules out a mod causing the problem.

If the garage you went to was Audi they should have been able to diagnose the fault, so there wouldn't be any point buying a VCDS of your own unless you are certain it can cure the problem.

I assume the garage also tested properly the battery, because a dying battery can cause unrelated electronic faults including limp mode.

Thanks, it was an independent garage not Audi, but im booked in with Audi end of August. But having spoken to Audi customer service I am skeptical they are going to do anything more than churn out some fault codes for me. Hopefully the technicians are better than the service reps. 

Battery was tested and voltage is reading fine.