A3 1.2 low oil pressure warning

[ssullivan25]

Hi all, I'm hoping you can help. We have a A3 1.2 2012 and the low oil pressure warning light has come on. I've change the oil pressure sensor and done an oil change, both were advised. This hasn't sorted the problem. I have noticed that the warning only happens once I hit 1600rpm.

Anyone else had this issue?

[Magnet]

Hello Stuart,

Welcome to the forum.

Are you saying the warning only comes on when the revs exceed 1600rpm? Normally such issues are more likely to occur at low revs. 

Also, can we take it the warning only comes on some time after the coolant has reached normal temperature?

kind regards, 

Gareth. 

[ssullivan25]

That's correct about the warning light, comes on once I go over 1600rpm so soon after i start driving which means that the coolant hasn't reached normal temp. I did notice the coolant was only just above min earlier so picked some up

[Magnet]

Hello Stuart,

Very strange. Could you tell us the make of the replacement oil pressure sensors.

I now appears your problem has escalated to also loosing coolant. Could you run the smoke test suggested under a recent post ‘Losing Coolant’ and let us know how you get on. 

As a priority, I would advise getting the actual oil pressure checked on an independent gauge by your  trusted local garage. If indeed the oil pressure is low, you run the risk of wrecking the engine by continuing to use it. 

Kind regards,

Gareth. 

[cliffcoggin]

Stuart.

I hypothesise, (meaning that I have never heard of it happening, though it is theoretically possible,) that the oil pressure relief valve may be opening too far as the engine speed rises. I believe that the pressure relief valve is within the oil filter so if my hypothesis is right the solution would be a new oil filter. This is close to speculation so I would welcome comments from others with knowledge. (Nudge, nudge, Gareth.)

[ssullivan25]

Thanks Gareth, I actually took it to a garage of a guy I've known and trusted for years. I spoke to him earlier as he found a couple of things out over the weekend. Hooked it up to his machine, no errors showing. He was surprised how the engine sounded as was expecting some noise to give him an idea of what the problem might be but all seems normal. He really has him confused. There's no smoke but will try a new coolant cap. We checked the turbo as well and that all seems good.

He has suggested changing the oil pickup tube.

I'm not driving the car at the moment as want to fix the issue first, the only driving that I've done is just to test it and the garage. 

Thanks Cliff, I changed the oil filter during the oil changed I did yesterday but still an issue.

[Magnet]

Good point Cliff, but I must admit that it’s location would be a bit of a mystery to me on this engine. The old vehicles - of which I have a couple even older than me! - now that’s easy. 

Oil filters and release valves? As I understand it oil filters were - still are? - fitted with a sort of one way valve to prevent the oil housed in them leaking back when the engine is not running, and this was really essential when some filters were fitted ‘upside down’ on the engine. 

Stuart has told us he changed the oil. Filter?? but guess so. Quality of oil filter ?? Yes, I know I have a ‘thing’  about only using good quality parts, bred from a distrust of some brands (once very reputable brand names) coming in from well east of the Thames estuary! 

Many thanks Cliff,

Kind regards,

Gareth. 

[Magnet]

Thanks for the extra information Stuart. 

Sorry to bore, but make of oil sensor and oil filter? 

No smoke when hot and revs. held at a steady 2000rpm for 2 mins. then. 

Good idea to change the coolant reservoir cap - always a cheap eliminator. 

Kind regards, 

Gareth. 

[ssullivan25]

I'm thankful you guys are helping me. I believe that is correct Gareth about the oil filter, I was told to change it as it could of collapse inside..... changing the filter is easy as it's top front on the engine. Getting to the sump was a tad more annoying due to 20 bolts holding a tray in under the engine. 

The filter I used was Bosch. Sensor was an aftermarket I believe, it has only 1 pin which is the same as I removed.

Will change the reservoir cap before the oil pickup tube. Altho the tube isn't expensive, just seems a bit of pain to do.

No smoke, to be honest I've not seen any smoke since my other half bought it a year ago.

[cliffcoggin]

Well if we assume the oil warning light is giving a true warning, the only other things that occur to me to cause low pressure are:

[1] the oil suction pipe letting air in through a hole or loose joint, which is probably why your mechanic suggested changing it,

[2] a loose or slipping drive connection to the oil pump. I don't know what sort of connection it is but years ago some cars had a tendency for the connection to wear and eventually fail.

[Magnet]

Hello Stuart,

To me, the next obvious must-do move would be to get the actual pressure reading assessed on a gauge. 

You don’t tell us the make of the replacement sensor. If it was anything other than a genuine VAG or Bosch, I would not be jumping to conclusions that it cannot be that because it is new! But the actual oil pressure reading will guide you on this. 

If indeed the actual pressure is indeed measured as being low then obvious culprits would be the oil pump, and possibly aggravated by bearing wear if the pressure has been low for some time. 

Let’s look at this with a positive result which shows the oil pressure to be acceptable. Culprits:- sensor (as mentioned), bad connection/wire break which can manifest itself by the engine torque movement aggravating the bad connection/ partial break. 

Coolant loss:- worth having the system pressure tested incase excess pressure is being generated, and obviously looking for leaks. It seems there is a dye which can be added to your (red?) coolant which assists with leak detection. Haven’t used it myself. 

Kind regards, 

Gareth. 

 

 

[o_user]

Hello guys,

i have a similar problem with my A3 2.0 TFSI 2005 model (156000Km). I have just changed the oil and the filter and when the engine temperature gets to the optimal running temperature 90*C at around 1600rpm( coincidence) i get the same oil pressure warning light. I have measured the oil pressure but when temperature was low and i had 2.6bar / close to 40PSI at idle speed and at 2000-3000rpm i had 5bar and a bit/ 80psi. Also the oil pressure sensor had a bad wire that according to the mechanic was fixed. The light stays lid for a short period of time (less then a minute) and disappears, but not for long as comes back again and again at random times. Can it be because of bad oil quality Castrol Edge 5W30 LL or the sensor or maybe something else at the engine? No visible leaks found. 

[Magnet]

Hello Octavian,

Unfortunately this thread is 11 months old ,and again the original poster didn’t return to update the forum on the outcome. Again, I can only suggest you send him a PM, and if you get a response, then it would be great if you could let the forum know what it was. 

In your case:- Castrol 5/30 should be fine, so this can be discounted. Make of oil filter? 

If you don’t get a meaningful response, then I would be tempted to replace the oil pressure sensor ( I would go with Bosch if not using a genuine Audi one) and carefully check all associated wiring.

Kind regards,

Gareth. 

[o_user]

Thank you for the reply Gareth.

I will go ahead and replace the oil pressure sensor and the oil filter but not in the same time so I can pinpoint the culprit. If this doesn't solve it I will change the oil with a different brand. 

Best regards,

Octavian

[Magnet]

Many thanks for coming back on this Octavian. I really like your logic of changing one thing and testing, before changing anything else. This makes complete sense, but few seem to follow the logic. 

What brand of filter did you fit recently? 

Oil being suspect? I wouldn’t think so. 

Kind regards,

Gareth. 

p.s. Oil pressure should always be checked when the oil up to operating temperature. That would be after at least a 10 mile run. Many believe the oil is up to operating temperature once the coolant gets up to normal, but that is not correct. 

 

[cliffcoggin]

Octavian.

You have used a decent quality oil so there is no point wasting money by changing it again. Your problem lies elsewhere.

[o_user]

29 minutes ago, cliffcoggin said:

Octavian.

You have used a decent quality oil so there is no point wasting money by changing it again. Your problem lies elsewhere.

Hi.

Due to my working hours and not being able to find a decent place to do the replacing of the sensor and oil filter on the spot and long waiting hours, I have decided to give it to some mechanic that will, according to him, clean the system, oil pump and all the components and verify if they are damaged plus the pressure test.

It will be done next week and I'll get back with what he found. 

 

Best regards,

Octavian

[o_user]

Hello guys. 

 

So the work done by the mechanic was as fallows: he clean the engine with a solution that he added in the oil, he verified the pressure of the oil, he cleaned the oil pan and check the oil pomp. He found that inside the oil filter house the pressure valve was missing so a new one was put ( the previous maintenance was done wrong and the mechanic from there throw it away 🤬). Oil was change from Castrol to Motion 5w30 and a new filter. He also checked the oil sensor pressure, clean it and put it back. Today I had to leave from the city were this was made and getting back to my busy home city and the oil pressure gauge got lit. I have call back the mechanic and he said that maybe the oil pressure sensor is causing this. I will see now change this sensor. I feel sorry that I didn't change together with the everything else. 

I need to sell this car 😂😂... 

[o_user]

Hi,

Just a small mention to my last post.. the oil that I have put was Motul and not Motion. Anyway, the problem was fixed not by replacing the oil pressure sensor that was also changed with a new original one and was resolved by changing for a third time the oil from 5W30 to 10W40.

All the best and thank you for support. 

[Magnet]

Thanks for coming back to the forum Octavian.

Please beware:-  the 10w/40 is normally a semi synthetic and not a fully synthetic oil - as it should be - so basically it’s the wrong oil for your car. If you feel you need to mask a possible lower oil pressure by increasing the oil viscosity, then I would suggest you change this oil to a fully synthetic 5w/40.

Kind regards,

Gareth, 

[Stevey Y]

58 minutes ago, Magnet said:

Thanks for coming back to the forum Octavian.

Please beware:-  the 10w/40 is normally a semi synthetic and not a fully synthetic oil - as it should be - so basically it’s the wrong oil for your car. If you feel you need to mask a possible lower oil pressure by increasing the oil viscosity, then I would suggest you change this oil to a fully synthetic 5w/40.

Kind regards,

Gareth, 

Hi its perfectly ok to swap from fully synthetic to semi synthetic as long as its the same spec  or you can even use a slightly thicker grade of semi synthetic or in fact mix the two at a push without any detrimental effect on the engine, both semi/fully synthetic start life as the same thing, mineral oil, semi synthetic is processed much the same as fully synthetic its pushed through pressure chambers until it converts into gas where the impurities such as sulphur are removed and friction inhibitors are added as well as flow additives and other molecular thermal stabilisers.

Fully synthetic is processed twice hence the higher cost as it has at the end of the process had more additives including detergent to keep the engine clean, if you look at vehicles that are used in countries  that always have high daytime temperatures often as not the manufacturers recommend a thicker oil as this prevents the oil ever reaching critical point and cracking which means the oil molecule structures collapse and the oil reverts to its native state, carbon, the flip side of this is Mobil 1 which has so much friction inhibitor in it as well as thermal stabilisers it will never ever reach critical point as whatever the temperature reached it will maintain its molecular structure and not crack, the downside to semi synthetic is that the oil change intervals are reduced due to it degrading more rapidly.

Steve.

[Magnet]

Many thanks Steve. Thanks goodness for the facility to have a free interchange of opinions. 
If we revert to Octavian’s issue of an apparent low oil pressure when using the correct specified oil viscosity, and his now satisfaction that the issue has been resolved by using a higher viscosity, is really akin to potentially adding ‘treacle’! until the ‘thicker’ oil holds its viscosity for some temporary period, and to some extent. How long?? 
Personally, I fear this will prove to be a short term dodge, but......

Re. semi synthetic vs fully synthetic? Of course, there are schools of thought that maintain oil-is-oil-is-oil, and that to spend any additional funds on recognised brands is simply financing the brand name, and equates to a waste of money. Maybe so and opinions vary. For what it’s worth, my opinion rests (with DIY) by buying the ‘apparent best’ at most competitive prices, since my labour is cheap! - but I always stick with the recommended specifications - I simply don’t see any benefits in deviating. This equates to using fully synthetic if fully synthetic is specified, or indeed semi synthetic where that is specified, and even straight mono grades in vehicles which are as old as me! I base this on my lack of in-depth knowledge of oil manufacture, despite being from a technical background, so I see no reason to challenge those who design engines and those who recommend the lubrication specifications for them.

 
Back to Octavian:- I would still stick with my suggestion of using fully synthetic 5w/40 if he feels he is prepared to mask possible underlying issues by moving from 5w/30, and can only add that there is a strong possibility that the fully synthetic variant will most likely ‘hold its viscosity’ longer than his semi-synthetic variant, resulting in him masking the issue for longer. Is the slight additional cost of using a fully synthetic rather than a semi synthetic worth the extra? 
Many thanks again Steve,

Kind regards,

Gareth. 

 

[o_user]

13 minutes ago, Magnet said:

Many thanks Steve. Thanks goodness for the facility to have a free interchange of opinions. 
If we revert to Octavian’s issue of an apparent low oil pressure when using the correct specified oil viscosity, and his now satisfaction that the issue has been resolved by using a higher viscosity, is really akin to potentially adding ‘treacle’! until the ‘thicker’ oil holds its viscosity for some temporary period, and to some extent. How long?? 
Personally, I fear this will prove to be a short term dodge, but......

Re. semi synthetic vs fully synthetic? Of course, there are schools of thought that maintain oil-is-oil-is-oil, and that to spend any additional funds on recognised brands is simply financing the brand name, and equates to a waste of money. Maybe so and opinions vary. For what it’s worth, my opinion rests (with DIY) by buying the ‘apparent best’ at most competitive prices, since my labour is cheap! - but I always stick with the recommended specifications - I simply don’t see any benefits in deviating. This equates to using fully synthetic if fully synthetic is specified, or indeed semi synthetic where that is specified, and even straight mono grades in vehicles which are as old as me! I base this on my lack of in-depth knowledge of oil manufacture, despite being from a technical background, so I see no reason to challenge those who design engines and those who recommend the lubrication specifications for them.

 
Back to Octavian:- I would still stick with my suggestion of using fully synthetic 5w/40 if he feels he is prepared to mask possible underlying issues by moving from 5w/30, and can only add that there is a strong possibility that the fully synthetic variant will most likely ‘hold its viscosity’ longer than his semi-synthetic variant, resulting in him masking the issue for longer. Is the slight additional cost of using a fully synthetic rather than a semi synthetic worth the extra? 
Many thanks again Steve,

Kind regards,

Gareth. 

 

Hi Gareth,

I totally understand this but please note that the oil I have put is synthetic and  NOT semi-synthetic and is for my type of petrol engine. Also I know that after 100k Km the viscosity of the oil should increase to accommodate for the wearing out of the parts ( correct?!) . I don't think you can stick with the same 5W30 until the end of lifetime of any engine, unless you change some of the inner parts. 

 

Kind regards.

 

[Magnet]

Thanks Octavian,

OK, your 10w/40 oil is fully synthetic. Things probably vary from country to country then. 
I’m yet to see 10w/40 in the U.K. in anything other than semi-synthetic, or sometimes ambiguously marked  ‘synthetic technology’. 
Probably different in Romania. 
Kind regards,

Gareth. 

[cliffcoggin]

I have feeling that the discussion of viscosities etc. is a red herring in this instance, and that there is an underlying problem that has not been solved. Let me explain.

The oil pump should be capable of creating much more pressure than is required by the engine in order that the pressure is adequate at idling speed, no matter what viscosity of oil is used, any excess pressure as the engine speed rises being bled off by a pressure relief valve to maintain a more or less constant pressure in the oil galleries. In this case the pressure is not high enough to prevent the warning light showing, so the question becomes why that should be. The possibilities that occur to me are:

[1] The oil pump is worn.

[2] The pressure relief valve is faulty.

[3] The engine bearings are worn.

[4] The pressure switch is faulty.

[5] The pump is sucking in air.

Unless anybody can add to that list, or disprove my logic, the problem must be one of those five things. I know that some of those parts have been renewed, but even new parts can be faulty or incorrect for that particular vehicle. Furthermore I see no investigation reported yet of items [3] and [5].

What say you chaps?