Always 1/4 quart low. Anyone Replace An Oil Level Sensor?

[Tommm]

About 2,000 miles ago I changed the oil and filter and added 7 quarts. The "dipstick" showed I was 1/4 quart low - same as before I changed the oil.

Last week I took the car to a play date with its PCA friends and it showed 1/4 quart low. I added 1/2 quart, went out for a half hour session in the rain. During the session, it showed 1/4 quart low. After the session it showed 1/4 quart low.

In case I haven't mentioned it, the "dipstick" is always showing 1/4 quart low.

Anyone have similar experiences? Thanks.

[ShocknAwe]

Disconnect your battery to force it to reset and check.

[Tommm]

Originally Posted by ShocknAwe

Disconnect your battery to force it to reset and check.

I was about to do that when I realized I did that in April. I had the battery disconnected for hours when I swapped the stock seat for the sport seat.

Is there another way to force a reset?

[ShocknAwe]

Originally Posted by Tommm

I was about to do that when I realized I did that in April. I had the battery disconnected for hours when I swapped the stock seat for the sport seat.

Is there another way to force a reset?

Dont know, sorry. Oil level sensors can go bad. I would physically measure your oil the next time you change it.

[captain slowly]

on the upside, its only 1/4 low, which is nothing to be concerned about

[Tommm]

Originally Posted by captain slowly

on the upside, its only 1/4 low, which is nothing to be concerned about

No, it may be a half quart over. It may be a full quart low. It may be two quarts low. But, the good news is it is not a quart over, so thanks for the insight. Where is Captain Obvious when I need him? Must have dialed the wrong number and gotten the wrong Captain.

Originally Posted by ShocknAwe

Dont know, sorry. Oil level sensors can go bad. I would physically measure your oil the next time you change it.

Thats what I plan on doing. I will probably just change the sensor next oil change. There goes $200.

[Juggernaut135i]

Originally Posted by Tommm

No, it may be a half quart over. It may be a full quart low. It may be two quarts low.
Thanks.

Thats what I plan on doing. I will probably just change the sensor next oil change.

You can take out the oil level sensor from under the car and clean it. Also maybe try to scan for any fault codes. Mine did this but it was because I had oil leaks from the valve cover, oil cooler, and oil housing. Also most from the PCV Valve. I change all 4 and added an oil catch can for good measure.

[Tommm]

Originally Posted by Juggernaut135i

You can take out the oil level sensor from under the car and clean it. Also maybe try to scan for any fault codes. Mine did this but it was because I had oil leaks from the valve cover, oil cooler, and oil housing. Also most from the PCV Valve. I change all 4 and added an oil catch can for good measure.

What did you do to clean it? Just wipe it down and reinstall, or did you play with the connectors?

I just disconnected the negative terminal and will reconnect it in about five hours when i leave the office. I think i will go under the car and play with the connection to see if that does anything.

When i first googled the sensor $48 sensors came up so i figured i would just replace it. The one for our cars is $195 so I will fiddle with the old one first.

[Juggernaut135i]

Originally Posted by Tommm

What did you do to clean it? Just wipe it down and reinstall, or did you play with the connectors?

I just disconnected the negative terminal and will reconnect it in about five hours when i leave the office. I think i will go under the car and play with the connection to see if that does anything.

When i first googled the sensor $48 sensors came up so i figured i would just replace it. The one for our cars is $195 so I will fiddle with the old one first.

I actually didn't clean the sensor itself but I'd imagine just a degreaser. Like brake cleaner. Let it dry then put it back in. May do nothing or it may fix it. I mean I know it sits in oil anyway but never know with these cars

[Tommm]

Originally Posted by Juggernaut135i

I actually didn't clean the sensor itself but I'd imagine just a degreaser. Like brake cleaner. Let it dry then put it back in. May do nothing or it may fix it. I mean I know it sits in oil anyway but never know with these cars

Were you getting a fault code? What prompted you to change it? If i take it out, it isnt going back in. I will fiddle with the connectors now because that doesnt require removing the part (draining the oil). If i remove the part it will be replaced, otherwise i have to wait another 5,000 miles to remove it again.

I would like to eliminate some potential caused before i drop $200 on a part. But, on the other hand, if it probably is the sensor, i wont waste time going to a dealer i am not fond of to pay them around $100 to tell me i need a $200 part.

[Juggernaut135i]

Originally Posted by Tommm

Were you getting a fault code? What prompted you to change it? If i take it out, it isnt going back in. I will fiddle with the connectors now because that doesnt require removing the part (draining the oil). If i remove the part it will be replaced, otherwise i have to wait another 5,000 miles to remove it again.

I would like to eliminate some potential caused before i drop $200 on a part. But, on the other hand, if it probably is the sensor, i wont waste time going to a dealer i am not fond of to pay them around $100 to tell me i need a $200 part.

Completely agree. I never got a fault code. Like I said I just had a lot of leaks and was shitting oil out my BOV. I'm just saying it's an option. I've never heard of the sensor failing though

Be careful to not over fill the oil, could build up too much pressure

[captain slowly]

Originally Posted by Tommm

No, it may be a half quart over. It may be a full quart low. It may be two quarts low. But, the good news is it is not a quart over, so thanks for the insight. Where is Captain Obvious when I need him? Must have dialed the wrong number and gotten the wrong Captain.


Thats what I plan on doing. I will probably just change the sensor next oil change. There goes $200.

I actually did read the thread. You say you changed the oil and put in 7 quarts. That's roughly 6.5 liters. That is the correct amount in a N55. I assume that would be the correct amount for your car, and that you actually know how much it takes. Lets assume again that you did put in the correct amount, and that the oil level sending unit is bad, and made you put in a 1/4 quart oil when you didn't need it. You're now 1/4 over, which is nothing.

The other possibility is that you have an oil leak, but then, I'd imagine you'd mention that, which you have not. Don't know what you're getting all worked up about, but what I do know is that logic is not your friend, in which case I'd just take it in to someone who has the ability to troubleshoot the car instead of just throwing money and parts at it.

[Tommm]

Originally Posted by captain slowly

I actually did read the thread. You say you changed the oil and put in 7 quarts. That's roughly 6.5 liters. That is the correct amount in a N55. I assume that would be the correct amount for your car, and that you actually know how much it takes. Lets assume again that you did put in the correct amount, and that the oil level sending unit is bad, and made you put in a 1/4 quart oil when you didn't need it. You're now 1/4 over, which is nothing.

The other possibility is that you have an oil leak, but then, I'd imagine you'd mention that, which you have not. Don't know what you're getting all worked up about, but what I do know is that logic is not your friend, in which case I'd just take it in to someone who has the ability to troubleshoot the car instead of just throwing money and parts at it.

I changed the filter and added about 6.5 quarts. It showed 1/4 low. I then added the other half, to total 7 quarts (6.5L = 6.8647 US Q (Difference between 6.8647 and 7 Q is 4 oz)) . Hence, my statement that I added 7 quarts. It showed 1/4 low.

I then drove it a few weeks, and it stayed at 1/4 low. I then added 1/2 for a total 7.5. That's almost 2/3 over if my math is correct (16 oz+4 oz=20'oz if none is consumed/burned). It reads 1/4 low.
To which you responded

Originally Posted by captain slowly View Post
on the upside, its only 1/4 low, which is nothing to be concerned about

Since i don't have logic, or the ability to troubleshoot, and I cant do new math like you can , please tell me something constructive, like where to get a new sensor for less than $195, or things an idiot like me can do to troubleshoot.

I would also appreciate understanding the flaw or absence of logic of not paying a dealer an hours time to diagnose that a part is bad when the part costs the same as the diagnostic time.

Thanks Captain

[Tommm]

Originally Posted by ShocknAwe

Dont know, sorry. Oil level sensors can go bad. I would physically measure your oil the next time you change it.

I plan on doing that, see below. I also disconnected the negative after lunch yesterday, and left it disconnected for three plus hours. 1/4 quart low.

Originally Posted by Juggernaut135i

Completely agree. I never got a fault code. Like I said I just had a lot of leaks and was shitting oil out my BOV. I'm just saying it's an option. I've never heard of the sensor failing though

Be careful to not over fill the oil, could build up too much pressure

Being a 1/2 to 3/4 over bugs me. I bought the car a year ago with 32k on it. I put another 17k on it, and the oil level hasn't moved. Since it was fresh oil when I bought it, i didn't worry about it until about 37k. First oil change I did was at 42K, and I didn't measure it, i got roughly 6 to 7Q out. Second oil change at 47K see above. Now I am at 49.7k and would rather not drain $40 worth of synthetic to measure if i am 1/4 or 1/2 over.

Before spending $200 on a sender, I planned/plan on removing the bottom panel and disconnecting the sender. Then drive the car for a few minutes and see if it throws a code. If not, and I still get the "OK" on the dash it means a bad sender doesn't throw a code and I will replace the sender.

If unplugging the sender throws a code, or warning, I am not sure what step to take. Retrofitting a dipstick instead of spending $200 on a sender is tempting.

[Juggernaut135i]

Originally Posted by Tommm

I plan on doing that, see below. I also disconnected the negative after lunch yesterday, and left it disconnected for three plus hours. 1/4 quart low.

Being a 1/2 to 3/4 over bugs me. I bought the car a year ago with 32k on it. I put another 17k on it, and the oil level hasn't moved. Since it was fresh oil when I bought it, i didn't worry about it until about 37k. First oil change I did was at 42K, and I didn't measure it, i got roughly 6 to 7Q out. Second oil change at 47K see above. Now I am at 49.7k and would rather not drain $40 worth of synthetic to measure if i am 1/4 or 1/2 over.

Before spending $200 on a sender, I planned/plan on removing the bottom panel and disconnecting the sender. Then drive the car for a few minutes and see if it throws a code. If not, and I still get the "OK" on the dash it means a bad sender doesn't throw a code and I will replace the sender.

If unplugging the sender throws a code, or warning, I am not sure what step to take. Retrofitting a dipstick instead of spending $200 on a sender is tempting.

Sounds good!!!

[Tommm]

Originally Posted by Tommm

I plan on doing that, see below. I also disconnected the negative after lunch yesterday, and left it disconnected for three plus hours. 1/4 quart low.


Being a 1/2 to 3/4 over bugs me. I bought the car a year ago with 32k on it. I put another 17k on it, and the oil level hasn't moved. Since it was fresh oil when I bought it, i didn't worry about it until about 37k. First oil change I did was at 42K, and I didn't measure it, i got roughly 6 to 7Q out. Second oil change at 47K see above. Now I am at 49.7k and would rather not drain $40 worth of synthetic to measure if i am 1/4 or 1/2 over.

Before spending $200 on a sender, I planned/plan on removing the bottom panel and disconnecting the sender. Then drive the car for a few minutes and see if it throws a code. If not, and I still get the "OK" on the dash it means a bad sender doesn't throw a code and I will replace the sender.

If unplugging the sender throws a code, or warning, I am not sure what step to take. Retrofitting a dipstick instead of spending $200 on a sender is tempting.

I missed the 37K oil change. Bought it at 32k. Changed it at 37k, 42k, 47k with Mobil 1. Should have read first oil change with oil I put in was at 42k and I didnt measure it. Since there is no dipstick, i have no way of knowing how much was in the crankcase when i bought it with 32k miles, hence no need to measure it at 37k.

[135iTime]

I have no idea how the level sensors work in these but in the Audi's I've owned a bad hood latch switch can cause this issue. Yes that sounds weird but with the way the logic for the level sensor works in those it won't read a higher level, only lower, unless it "knows" the hood was opened.

[Tommm]

Originally Posted by 135iTime

I have no idea how the level sensors work in these but in the Audi's I've owned a bad hood latch switch can cause this issue. Yes that sounds weird but with the way the logic for the level sensor works in those it won't read a higher level, only lower, unless it "knows" the hood was opened.

And when one of the cells of the battery went bad on my buddies roughly 2000 A4, the sunroof was wonky.

Thanks. I'll fiddle with the latch too.

[Tommm]

I finally got the time to go under the car yesterday. I disconnected the oil level sensor, drove a bit, and when I checked the oil i was told "inactive". I reconnected the sensor and am 1/4 quart low.

The system check came back "OK" so the sensor is not connected to that function.

I didnt tap the sensor with a hammer which with my luck would have cracked the oil pan.

Any suggestions before i drop $200 for a sensor.

[Tommm]

I played again today. installed the oil drain valve and drained two quarts. the sensor was halfway between the first and second line so I was more than a quart low. added a half and it said add a half.

turns out I was reading the electronic dipstick wrong. the quart is the two inner vertical lines, the area outside those lines is more than a quart low, and overfilled. I was at least a half quart over, but the sensor was saying full, not 1/4 quart low as one would think from the four lines.

Hope this helps someone in the future.

[Gangplank]

Here is what it looks like when you are at the Min. (Need to add).

[Tommm]

Yours has min max. Mine is at the full mark and says OK. Ok, yes, but it looks like it js 1/4 down because of the blank in the overfill area. Im not happy that mine didnt pick up it was 1/2 qt overfilled. Since i do my own lil changes im not too concerned about that.

The top picture is what it showed a half quart over.

If one changes their own oil i recommend adding 5.5 of the 7 quarts, running the motor to test the sensor, then add 1 qt l, test again, then top off the final 1/2 qt.