My attempt to trick Audi - Oil level sensor

I bought my Audi TT through Autobidmaster/Copart. It was listed run and drive. The transporter even drove it off the trailer. But it had a huge crack in the oil pan and subframe. It sounded fine.

But in my cheapness at the time I bought a replacement pan that didn't have a level sensor. It was $80 versus $500. I figured I'd toss the cheap pan on first and if the engine had issues I'd end up biting the bullet and paying for used engine that would have a good pan and sensor. 
 

I had hoped it was something I could code out via VCDS, but no luck. Or something that someone else had a fix for. Again no luck, lots of posts of people having sensors failed and replacing them, but no bypass. Oh, one post said to jump two pins of the harness, all that did was blow the fuse. 
 

I'm no expert at all but I'm assuming the sensor gives some resistance based on how much oil is covering the shaft of it. So my plan is hopefully to buy a cheap sensor, $25 set it up in a fake bath of oil and try to see what it puts out as resistance. 
 

Step one ordered new sensor. 
 

Step two will be, needed to do this anyways is to get an erWin day subscription and download everything I can for the wiring of the TT, plus my other VWs. Not absolutely necessary for this but I needed to do it for other reasons. 
 

Step three use the old oil pan as test bed so I don't have to be under the car messing with the connector at first. 

So this thing monitors oil temperature?    You are considering putting it into a fake oil reservoir so it always reads oil it present.  That reservoir's oil would never get up to the temperature of oil in a warmed up engine.

But does that temperature sensor send info to the ECU and tell it how much fuel to send to the fuel injection depending upon the temperature reading?   

I realize that the ECU may be using a completely different sensor for cold engine fuel injection decisions but its a thought.

In reply to jharry3 :

Only oil level as far as I'm aware. Oil pressure and temperature are measured elsewhere in the system.
 

The goal is to study/learn how the sensor operates and then rig up something like a small resistor to mimic that. So the final product would be a little bundle that plugs into the factory harness. 

The other option would be buy a new oil pan with the sensor $500+ 

Funny thing is the inexpensive pan is cast with the level sensor shape, but I'd have to drill holes precisely to install a sensor. Even with it being cheap I don't want to make the effort, change the pan, then have it possibly leak. 

Black electrical tape over the oil level light?

I mean, you will have a non-working sensor anyway, what's the difference if you just make it easier to ignore the warning light?

I wonder if there's some sort of troubleshooting guide that has the resistance range. Or you could recreate ideal conditions and measure resistance 

In reply to dan0 :

I must have misunderstood this detail that was posted:

In reply to SV reX :

I've ignored it for two plus years, figured it's time to make the light go away. Plus it shows up in the center display quite large. 

In reply to jharry3 :

My bad, I grabbed the first stock photo. I guess it could monitor temperature. But it's been without for two plus years and no issues. 
 

I have a VCDS scan tool. I can go in and look if there is a measuring block for oil temperature and if it is possibly reading from another source. 

In reply to Peabody :

That's my plan. The erWin system online is factory service source. So when I pay the $35 for a day access I'll see if there is anything in there. Otherwise my sensor purchase I'll set up a physical test. 
 

Plus I'll download everything I can for my 2004 and 2011 Touaregs, so it will be worth it. Because at some point I have a full 2004 harness to dissect the wiring for the rear differential lock so I can swap a factory rear locker in. Of course being a VW it has its own control module, so not just a couple wires to a motor and switch. 

Is there a blank boss on the cheap oil pan for the sensor?  If so, cut out the hole and tap and drill the bolt holes.  Install sensor.

In reply to Noddaz :

Because don't want to mess it up. Then I'm stuck chasing a leak or replacing the pan again. Then back to the dilemma of expensive pan with sensor $500 or cheap pan no sensor $80. 

I don't think it would be very hard to mount it in your new pan without leaking.  It would be the quickest and easiest solution and would give you the benefit of having a working oil level gauge.   
 

In reply to jfryjfry :

I haven't looked closely at it in a while but I recall while it had the indent in the pan for the sensor it wasn't marked well for it. I guess I'll consider trying if it is marked well.

Decent size hole. And the three holes to bolt in need to be accurate to the corresponding umm nipples? on the interior of the pan. 
 

Well E36 M3. I needed to upgrade my VCDS license for more VIN to reset the service reminder on my mom's EOS. 

Plus my service light has been on the TT since I bought it. So tonight I said, let's reset the service light. Did that, then said let's go into instruments and see if there's anything about oil level. 
 

Found this.

Maybe it will come back, but two key cycles so far and no light. Although now the top section of the cluster seems to empty without the big oil sensor light. 
 

The saga over? Or will continue? 

Oh wait, since it got brought up here tomorrow I'll check measuring blocks and see if there's an oil temperature reading somewhere in the ECU, that pulls from a different sensor. 

So in the MFI there is a oil temperature display. Which is reading blank. There is a fault in the Instrument for the level sensor. 
 

But in checking the measuring blocks in the ECU, there is no oil temperature block. No fault for the sensor in ECU either. 
 

So my assumption is the sensor is only reporting to the instrument cluster and has no bearing on how the ECU manages operating the car. Yes it would be nice to know oil temperature, but I'm also not tracking the car or putting it through a lot of abuse.