Hi everyone. I have the dreaded low oil pressure issue with my Audi A5. I know this is common but I've scoured the forum and I can't find an example that quite matches my situation and combination of fault codes. I'd be incredibly grateful for any guidance as I love this car and want to get it fixed.

The car is a 2013 Audi A5 (8T3) 2.0 TSFI with the EA888 Gen3 engine (CNCD). It's done about 84,000 miles. Low oil pressure is confirmed (readings below) and I've taken some initial steps to try and rectify the faults. I'm not a mechanic in any sense so all the difficult work (replacing oil pump) has been carried out at a local garage. They are now suggesting an engine teardown by someone that is more familiar with this particular engine.

Manual pressure readings by garage:
@ Idle = 0.7 bar
@ 2000 = 1.6 bar
@ 4000 = 3.8 bar

Fault codes:
  • P164D - Reduced oil pressure switch: When engine warmed up and idling, "Reduced oil pressure. Switch off engine" red light appears. Disappears with increased engine speed (>1000rpm).
  • P164B - Oil pressure switch: When engine warmed up and sitting around 3000rpm, EPC warning light comes on with "Do not exceed 4000 rpm" message. Limp mode activated until engine restarted. Limp mode not as extreme as with P168D.
  • P168D - Oil pressure switch 3: When engine warmed up and sitting around 1500rpm, EPC warning light comes on with "Do not exceed 4000 rpm" message. Full limp mode activated until engine restarted.

Parts replaced so far:
  • Oil filter 06L115562B
  • Filter housing 06L115401L
  • Oil filter retaining post 06L115678Q
  • N428 Oil pressure control valve 06K115243L
  • N522 Piston cooling jet control valve 06K115243AB
  • PCV valve 06KI03495BL
  • Oil pump (don't have part number to hand but it was OEM)

I also ran some Seafoam through and replaced oil with Liqui Moly (5W-40) when changing the filter. No evidence of metal in the oil or filter. No sludge in the sump pan. No blockage in the pickup pipe.

I've driven 7k miles with this issue and aside from the fault lights everything seems fine. Well, as long as I avoid sitting at <1000, 1500 or 3000rpm for more than a couple seconds lol. Regardless, I need to get the issue resolved.

What I'm hoping for is some guidance on how to proceed. Does the nature of the issues at certain RPMs or the location of the sensors point towards a particular component? How can I (or a garage) diagnose the problem to identify what component is causing the problem? I have an OBDeleven scanner if that helps.

Really appreciate any help.

Cheers,
Scott