Oil Level Sensor fault (diagnosis / testing)

[rAy6]

Hi all,

As dash warning lights are now an MOT failure, I need some help with the oil level sensor on my 2013 2.0tdi 177ps.

The oil level sensor warning is always on (I've checked the level plenty of times with a dipstick, it's fine, it's been this way for over a year and has been through an oil change, no oil lost), and I'd like to diagnose it before buying a replacement. No doubt it's not something to be messing around installing and reinstalling etc. as it sits at the bottom of the sump so it's effectively something best done during an oil change, not to mention removing and reinstalling the undertray each time. At the last oil change I removed the sensor and thoroughly cleaned the sensor out, upon reinstall and post oil change, it flagged straight up when the engine was started.

Is there are a way of testing the wiring first, to ensure that the wiring is fine... a way of jumping / putting a load onto the 3 wires to recreate a "healthy" oil sensor? My brake pad warning lights came on a while ago even though the pads had 70% material remaining - turned out to be a bad ground on the sending wire, so that was fixed just with wiring.

In addition to a testing of the wiring, I'm struggling to find the right sensor. The one in there is labeled "Hella 04L 907 660A" "6PR 010 418-06" "PA66GF35". I've not found any for sale with those numbers. The closest is "04L 907 660B" but the 6PR... number is quite different "6PR 013 680-061" and the place with it in stock refused to sell it, as it showed up as not correct for my car.

Thoughts, advice all welcome.

Thanks

[Elansear]

Not sure that it would fail an MOT for an oil level warning as you can prove that the level is correct with a dipstick, surely the warning is because the manufacturer decided to provide it , not because it was obliged to. Your washer level could be low giving the same warning, but as long as they work it will pass. It's a warning, not a failure indication of the oil level, same with a break pad warning if the pad and disc are in a safe condition and they work safely that should be OK, what if pads without a warning wire were fitted, then you would not get a warning light. I would drop into a local test centre and put the question to them to be 100%.

[morski]

pm me your VIn and i can get you the correct part no for your car

[rAy6]

I couldn't agree with you more Elansear!

Not sure that it would fail an MOT for an oil level warning as you can prove that the level is correct with a dipstick, surely the warning is because the manufacturer decided to provide it , not because it was obliged to... It's a warning, not a failure indication of the oil level, same with a break pad warning if the pad and disc are in a safe condition and they work safely that should be OK, what if pads without a warning wire were fitted, then you would not get a warning light.

Interesting you mention the brake pads - There were two warning lights - oil sensor and brake pads. The brake pads are a bad connection (warning light only comes on when wheels are turned about half way, I had fixed it a year ago but recently it started coming on intermittently, think it's some corrosion from over the winter period - never thought to look at it for this MOT as it went through the last MOT with it lit, but they changed the rules from this April onwards). The pads are only about 30% worn (as in 70% material remaining), I explained about the wiring and even though they acknowledged that the brakes were all fine, purely the fact that warning light for the pads were on, was reason for them to fail the MOT, so they wouldn't carry it out (they were doing their Vehicle Check pre MOT). I checked the .gov site and it lists brake pad warning lights there as a failure.

So back to your quote - exactly... Most cars don't even have brake warning lights, it's effectively an optional extra and logically the physical check should override the well known fact that sensors and wiring are usually unreliable. Though, we're dealing with government logic here. Ontop of that - as you say - they are simply a warning / notification. They come on somewhere around 70% worn - i.e. "they're fine now but be prepared to change them in the future" which could mean a good few years of use, depending on driving style and mileage etc. A very interesting point to note is that there is no guideline on what a worn pad is... no mm reference like with a tyre. A brake pad could have 0.5mm of material left and still pass an MOT (providing no warning light is on with the new rules). So in effect, a car with a brake warning light system that is fully functional (i.e. no faults in wiring / sensor) with brake pads at ~30% that have potentially years of life left, would fail, because the sensor is lit (as the manufacturer set it to ~30% - and with anything like this they build in a huge safety margin as they need to account for a the average public forgetting and putting things off etc., or for the guy towing a maximum load over hilly conditions for hundreds of miles). So it's not an indication that the brake pads are worn out, simply that the brake pads will need changing in the future, so even though the pads themselves are more than ok, they don't need changing, they won't pass an MOT, even though they're fine, only because they need to be changed at some point in the future. It's mad. It would be like punishing someone for shoplifting due to having a few things in their shopping basket - even though they're in the middle of an aisle.

So there could be a situation where two cars are side by side at an MOT station, with identical pad thickness of say 30%, one with brake wear sensors, the other without, and only one is legal to drive - even though they are both identical, and in reality can probably drive on the pads for a long while. Effectively the government is forcing people to change parts that don't need changing. It's a genuinely bizarre non-thought out rule. Would love to support some kind petition on getting this rule changed (i.e. phsyical check overrides sensor), if anyone knows how to.

For the oil sensor light, it's a bit of a grey area. The .gov site mentions that warning lights for example brake pads, airbag etc. are reason for fail, but it's a bit ambigous in terms of what's covered. The issue I had was that because the oil sensor light was on, they wouldn't run the engine up to temp for emissions in fear of engine damage, therefore would refuse to carry out the MOT. I explained that the level is fine, I check it regularly with that proven method known as a dipstick, and they should do the same, ontop of which I'll sign a disclaimer that I accept all responsbiltiy etc. They weren't having any of it, of course.

I would like to sort the oil sensor out, partly because the warning is annoying each time the car is started, also for future MOT's. As they refuse to test, it's effectively not able to pass an MOT as they won't carry out an MOT. It would be ideal to find a wiring diagram and diagnostic method - i.e. put some kind of load onto the wiring plug to replicate a healthy sensor, to ensure that the wiring is ok, before draining the sump and adding the cost of replacing the oil (ideally will do this during an oil change).

Thanks in advance.

Snap of MOT refusal / predicted failure:

mot.jpg

[Elansear]

Hi I can see some logic behind the break warning light, as most are a voltage to ground method then easy to get round !!! The oil level warning situation is not acceptable, as you can prove the level is correct to them. Are they saying that every vehicle presented for test that they pull the dipstick to check before accepting it for test... If so then they can do the same to yours, but of course they don't, it's just an excuse by a jobsworth, I would ask them to provide evidence from DVLA that they were correct to refuse to test. Best bet use another tester, and if you happen to pass a HGV test centre drop in and seek there take on it, as most are employed by DVLA. The world has gone mad......

[Artiglio]

Not wishing to be argumentative, but ABS has been a requirement on cars from around 2004, on most of the cars i’ve had a fault with the abs system / brakes etc will light up the warning light on the dash. Yes the car will still stop on the brakes which will function perfectly as brakes but may have no abs function.
My partners citroen suddenly lit up like an xmas tree , would’nt reset, into halfords who diagnosed a failed abs sensor on one wheel, they changed it but made no difference, they said it needed to go to a main dealer as it looked like a wiring fault , went to a local dealer, who identified a failed reluctor ring, as discs and pads were pretty worn made sense to do them all rather than a single ring. Problem solved.
But car would never have passed an mot without it being fixed, brakes more than capable of stopping car.

[Elansear]

Hi agree in respect to ABS but the issue posted relates to a pad wear warning only and not an ABS issue. In most cases an ABS issue would report an ABS warning and also probely ESP with if able a worded warning for ABS. You are correct that this type of warning would be an MOT fail , hence there is usually a switch to prove that this warning light comes on and I believe is part of the test to switch the light on to prove it works, it's not unknown for people to remove/cover such a light. Yes agree if it's ABS stop and get resolved...