Purchased an Audi SQ5 (2016) with 47k miles back in Dec 24. Prior to purchase had a full RAC check carried out on it, but always noticed a slight smell coming from underneath, had exhaust checked and emissions tested all clear. Roll on 6 months and 12k miles, DPF light cam on after a long motorway drive, carried out manual regen (drive at 2500 rev etc etc) all fine 2 weeks later engine light appeared, fault code was for blocked DPF (never went into limp mode, or lost performance). Mobile DPF came out tested and said no pressure in DPF and with the smell said it must be cracked. Took to a local Audi specialist who said DPF could not be regenerated and new one required. £3700 later car back after having DPF replaced, engine and turbo checked, injectors checked, EGR Checked, Air Breather replaced along with Air Mass sensor, but I still have a foul smell coming from exhaust/underneath the near side, now I am no mechanic, and car is going back in to be checked after 2k miles with the new DPF, but that smell cannot be right, and hoping that someone else may have had the same issue, or provide some guidance. The smell is not all the time, but you can smell it in the cabin and not just outside when it occurs
Many Thanks

Edited June 5, 2025Jun 5 by Jason Bax

The stink may be unrelated to the DPF. For example paint or oil or underseal spilt onto the exhaust will slowly be burning off. There may even be a dead animal decomposing.

I gutted my DPF after many attempts to clean it with all sorts of chemicals/soap etc etc i now have a smokey smell and the mrs hates it,wasnt sure wether it was all that crap i pumped thru it?? or that its because it hasnt got a DPF now???  can you describe the smell??

 

Edited June 12, 2025Jun 12 by Hellsfire555

Thanks Paul,

Jason joined and posted on 5th June, but is yet to revisit and come back with any comment.
Good, isn’t it? 
Regards,

Gareth. 

Any smell in the car I’d be looking at ant-bacterial treatment on air conditioning. You can get similar smell from screen wash reservoir if not using correct additive. If it’s from the car under load, next thing to check would be catalytic converters.