Intermittent oil pressure warning Audi A4

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Good Sunday afternoon BITOG.

2004 Audi A4. 3.0 V6. ~178k.
The oil pressure warning comes on intermittently. The oil level is correct. I am hoping it's either a faulty oil pressure sensor or faulty bypass in the filter, but research has lead me to believe the oil pickup screen may be plugged up with junk.

Long story short, it was purchased as a daily driver to keep the miles off a beloved vehicle, but an exhaust cam lob was gone and the engine ended up getting replaced with a junkyard engine back at ~120k. VW502 oil and German Mann filters have always been used since the transplant.
 
Originally Posted By: rooflessVW
Pop a sensor in it. They're $15 or so if I recall correctly.



Yes sir.

Looks like it goes right above the oil filter housing.
 
Is there any pattern to when the warning comes on? Such as less frequent when cold (higher oil viscosity and higher pressures), but more frequent when sitting in a roasting hot traffic jam, or flickering at idle after getting off a long highway run (oil at operating viscosity and thus lower pressures)?

Does blipping the throttle to raise the RPMs off idle make the warning stop?
 
If the problem isn't sensor related then you might have a worn oil pump drive chain. At the age and mileage I wouldn't be surprised.
 
Originally Posted By: VeryNoisyPoet
Is there any pattern to when the warning comes on? Such as less frequent when cold (higher oil viscosity and higher pressures), but more frequent when sitting in a roasting hot traffic jam, or flickering at idle after getting off a long highway run (oil at operating viscosity and thus lower pressures)?

Does blipping the throttle to raise the RPMs off idle make the warning stop?


From what I understand, it's when the car at full temperature and is shifting through gears during stop and go traffic. No issues on highway driving.
 
Originally Posted By: dlundblad
From what I understand, it's when the car at full temperature and is shifting through gears during stop and go traffic. No issues on highway driving.


Since the oil level is sloshing back and forth inside the pan while driving in traffic; and since the oil level is steady on the highway; that leads me to suspect the oil level is too low and you have the wrong length dipstick.
 
From past experience, Drop oil pan and clean sludge off oil pick-up screen........Audi’s extended oil change intervals of the early 2000’s are to thank for that.
laugh.gif

This is coming from a previous owner of a 2003 A4,
 
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Originally Posted By: das_peikko
Originally Posted By: dlundblad
From what I understand, it's when the car at full temperature and is shifting through gears during stop and go traffic. No issues on highway driving.


Since the oil level is sloshing back and forth inside the pan while driving in traffic; and since the oil level is steady on the highway; that leads me to suspect the oil level is too low and you have the wrong length dipstick.


Good observation, but it's had this dipstick for the last 60k miles.

I will say it is hard to read since it's black plastic, but I've confirmed the level many times after a fresh 7 quart oil change as well.
 
Quote:
From what I understand, it's when the car at full temperature and is shifting through gears during stop and go traffic. No issues on highway driving.

So, on acceleration or deceleration, but not at idle?
What about immediately after exiting the highway and coming to a stop at idle?


Quote:
Would I be asking for trouble by using a Permatex equivalent?

Permatex Ultra Black is very similar, but I would recommend going for the OEM specified material just to be safe, unless someone else here has good experience with a substitute.
 
Might be worth pulling the fill cap to see what the engine looks like inside. A co-worker's A4 had the same issue with a 1.8T engine, and it ended up being pretty sludged inside from PO neglect. The oil light would flicker at hot idle, and putting a gauge on it revealed the engine only had a couple PSI at idle. It scorched the turbo soon after and he sold the car.
 
The oil pressure wire is frayed. Not too bad, but wire is exposed.

I couldn't get to the oil pressure sensor so I gave up and removed the pan. Took 15 mins if that.. The engine was spotless. I also removed the oil pump chain cover. The chain was tight and once again, everything was spotless. I fiddled with the sensor connector for about 30 mins, sacrificed one of my picks to shorten it up since room was tight.. there was no way. Finally gave my Autozone clearance Dorman electrical connector disconnect tool a try and it came off with the first attempt.

I used the hook shaped tool.
https://www.summitracing.com/parts/rnb-8...BSABEgKMpPD_BwE
 

That wire is at a bit of a harsh angle and it was pretty tight. The disconnect tab was also perfectly aligned with that bump in the engine block, which made seeing and getting to it that much harder.

 
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I just did one of those. I have the pin removal tools (if you work on VW/Audi you need these) that make it a 10 min job, all the empty OE connectors are available.
 
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