My 2007 Audi a4 S-line 2.0 "Oil Pressure Light" Keeps beeping. My oil level is fine, I see no lights. Also I have a check engine light on "bank 1 too lean". They changed the filter, mass flow sensor, and even did a smoke test and it passed. Just bought this car about two months ago off a third party dealer and I been having nothing but problems. I love the car, but its just been a headache. If this is a problem I could fix myself that would be great.

 

First thing is the oil pressure is probable the most critical item for the engine next to the coolant. An engine with low or no oil pressure at all will not run for more than a few minutes without serious damage or simply seizing up. Apparently since you've not had this happen yet, I suspect you do have oil pressure and it could be just the sensor not reading correctly.

A lean issue means there is an air leak or vacuum leak somewhere. My first suspect is the PVC valve. If you crank the engine, let it idle, and try to remove the oil filler cap on the valve cover but you feel it being sucked back to the opening, the PCV valve is bad. It's an easy fix on most Audi's. But since you smoke tested it, that might not be the issue. But it only takes minute or two to check so I'd check it anyway.

A Mass Air Flow sensor issue will give you other issues and since replacing it did not fix the issue, that was not the problem. Not to mention $200+ out of your pocket. The best way to test for a bad MAF is to simply unplug the stupid thing. Seriously. The engine will adapt and run itself using the O2 sensors and it will run just fine. You will get a MAF error on the ECU but the car will run fine. The problem is if the MAF is sending bad data to the ECU, the ECU will use that data and it will cause some weird running issues. If you unplug the MAF and the ECU is not getting said bad data from the MAF, it will use the O2 sensors to adjust the air fuel mix. It will run much better. But since you've also had that replaced, that is not the issue here.

Another place you can get a small air leak that will trip a lean condition is the hose from the auxiliary air pump in the air filter box to the metal piping on the engine. Especially close to where the rubber pipe clamps to said piping. It really doesn't take much more that 1mm hole to induce enough extra air to cause the issue.

Like I said, the oil pressure issue is more than likely the sending unit. It is located down low on the engine and is prone to get sludge build up in the tiny hole in the end that goes to the sensing element inside it. Sometimes you can run a oil system cleaning additive like Sea Foam (I love the stuff) to help clean the sludge from the engine. They may help clean the end of the sensor out also. Replacing the sensor isn't all that complicated but it can be hard to get at on some cars. I'm not exactly sure where yours is but I suspect it's pretty close to the oil filter.

Change the oil and filter on it and run about a 1/4 can of Sea Foam with the oil and let it do some cleaning. Run it a couple of weeks and change the oil and filter again. Add a little more Sea Foam and run it until you would do a regular oil change. During that the time you're running the Sea Foam in the oil, the oil light issue may go away if it cleans the end of the sensor out on it's own.

 

Dave thanks for all this information. I am going to try this and will let you know how it goes!