[Iamcarnovice]

Last week, I got a coolant level indicator sensor activated in my 2015 VW Polo TDI when i started it for the first time in the morning!

I immediately checked under the hood to find that the coolant level was not bad. It was hovering between Min and Max in the tank. I topped up a little bit of water but the indicator refused to go until engine reached its max
temperature of 90 degrees.

I went to the fuel pump got some premixed coolant and topped a little but the problem refused to go everyday in the morning when I first started the car, the Indicator would come up.
Eventually, took the car to my regular garage and I was told that there could be a leak in the EGR cooling system. I was not very convinced that there could be a leak in the coolant flow system and still coolant level is above the min mark and so I took the car to another garage (about whom I know nothing, but they claim to be VW experts too). These guys brushed off the EGR leak issue and told me that the particles were remains from the oil leak from my earlier valve door replacement where the coolant was mixing with engine oil.
They just asked me to top up my coolant can with RO water (which I did to a little over the max level) and asked me to run for a day and see. Viola - Indicator stopped now.

My question is simple - Why would the tank indicator behave erratically? Would it still be an EGR leak without actual fluid draining out?

PS: If I dont have to do anything more, I will flush out the water and change the coolant completely.

Thank you!

[hserus]

Originally Posted by Iamcarnovice

Last week, I got a coolant level indicator sensor activated in my 2015 VW Polo TDI when i started it for the first time in the morning!

Fully drain, flush several times with DISTILLED water - not RO water, tap water etc, till only water comes out on draining - and refill the coolant - especially don't top up with a different coolant brand from a petrol pump.

VW is very specific in the kind of coolant it requires and either OEM coolant or some very specific brands (Glysantin for example) support the spec it requires.

So get the OEM coolant to play safe.

Get the car ECU scanned for any issues - if it is EGR related as you suspect, you will get alerts.

[Iamcarnovice]

Originally Posted by hserus

So get the OEM coolant to play safe.

Get the car ECU scanned for any issues - if it is EGR related as you suspect, you will get alerts.

Thank you! We did a ECU scan and nothing apart from coolant low was read. The RO water was just to check for leaks.

Will be getting coolant flushed, tank cleaned and changed to OE tomorrow if the indicator keeps quiet tomorrow morning as well.

[Jeroen]

If the level remains stable there are no leaks. The comments around EGR are ridiculous. It doesn’t appear you have a leak anywhere, just an alarm that should not be there. So suspect the alarm. If you are getting a cooling liquid alarm with sufficient level in the cooling liquid reservoir, the problem is with the sensor and or the cabling.

Not sure if yours has a float? They sometimes get stuck or Split which means they don’t float anymore! Check the cabling and the connectors. My money would be on the sensor just being broken. Float or otherwise.

Do take notice about the comments on the cooling liquid! Very important! Only add the appropriate stuff, nothing else will do.


Good luck

Jeroen

[hserus]

Either that or the coolant has gone unchanged for a long time and has lost its chemical properties so isn’t doing it’s job now?

Originally Posted by Jeroen

If the level remains stable there are no leaks. The comments around EGR are ridiculous. It doesn’t appear you have a leak anywhere, just an alarm that should not be there. So suspect the alarm. If you are getting a cooling liquid alarm with sufficient level in the cooling liquid reservoir, the problem is with the sensor and or the cabling.

[Jeroen]

Originally Posted by hserus

Either that or the coolant has gone unchanged for a long time and has lost its chemical properties so isn’t doing it’s job now?

No, that does not explain why the level indicating would not work properly

Jeroen

[hserus]

Originally Posted by Jeroen

No, that does not explain why the level indicating would not work properly

Jeroen

Where is this indicator measured from? The radiator or the coolant reservoir?

If he flushed the coolant reservoir by topping it with some bottled water and the error temporarily went away, and moreover he mentions “particles” but doesn’t go into detail - maybe he has a clogged radiator and that’s interfering with coolant circulation so while the tank is full it doesn’t reach where the sensor is located? Not entirely sure the reservoir itself has the sensor placed there.

[Jeroen]

Originally Posted by hserus

Where is this indicator measured from? The radiator or the coolant reservoir?

Coolant reservoir. And it is a capacitive type of sensor, not a float. So they go bad sometimes.

Lots of information on the net:

https://www.youcanic.com/guide/vw-te...t-flashing-red

Also, just to add, you do need a VW (VAG) specific OBD scanner and not a generic one to find any error codes.

Jeroen

[Iamcarnovice]

Originally Posted by hserus

Where is this indicator measured from? The radiator or the coolant reservoir?

If he flushed the coolant reservoir by topping it with some bottled water and the error temporarily went away, and moreover he mentions “particles” but doesn’t go into detail - maybe he has a clogged radiator and that’s interfering with coolant circulation so while the tank is full it doesn’t reach where the sensor is located? Not entirely sure the reservoir itself has the sensor placed there.

So, this is related to the oil leak and the replacements (Oil cooler and Valve door) I did to fix it. Oil was mixing with coolant and the coolant tank got mixed with engine oil. I got it flushed, got the oil leak fixed and changed the tank.

However, the coolant tank still has some "particles", perhaps the remaining engine oil deposits from circulation says the garage. This needs to be flushed out by opening the radiator which will be done today or tomorrow after which I will be getting OE coolant.

[Jeroen]

Originally Posted by Iamcarnovice

So, this is related to the oil leak and the replacements (Oil cooler and Valve door) I did to fix it. Oil was mixing with coolant and the coolant tank got mixed with engine oil. I got it flushed, got the oil leak fixed and changed the tank.

However, the coolant tank still has some "particles", perhaps the remaining engine oil deposits from circulation says the garage. This needs to be flushed out by opening the radiator which will be done today or tomorrow after which I will be getting OE coolant.

As I mentioned earlier your Polo has a capacitive type of level sensor. So contamination could be the problem. I believe you should always try to come to a diagnoses first, before starting to swap bits and pieces, or in this case flush the whole system.

If I were you I would still check the electrical connections first. Take a look at the cooling reservoir and the (various) cable(s) connected to it. Look for obvious damage, chaffing. Pull each connector. Was it properly attached to start with, sometimes they become loose. Closely inspect both ends of the connector for corrosion/dirt. If you have it, give both ends a blast with some electro cleaner and push them all back together again. Check if that cleared the level indication.

If not have a look inside the cooling liquid reservoir. Do you see an oil film on top? If so, it might be advisable to flush the system regardless. Try and see the level sensor inside the little reservoir. Take a long (clean) screwdriver and wind some non fluffy cloth around it (e.g. part of a tea towel). Scrape alongside the level sensor carefully. The idea is to clean it, dislodge any accumulate dirt/oil on the sensor. Check if that clears the fault. If it does not, I don’t think it makes any sense to flush the cooling system.

You might get lucky and it is just a bit of accumulated dirt (i.e. oil film). If not it most likely the sensor. The only way to diagnose is to get it hooked up to a proper VAG type of OBD scanner. The sensor generates a VW specific code that general OBD scanners do not pick up.

If you search the various Polo forum in the world, you will see this is not an unknown problem. Many people had to replace the sensor. Not sure if VW carries the sensor separately or the complete liquid cooling reservoir.

Good luck, let us know what you find.

Jeroen

[Iamcarnovice]

Originally Posted by Jeroen

As I mentioned earlier your Polo has a capacitive type of level sensor. So contamination could be the problem. I believe you should always try to come to a diagnoses first, before starting to swap bits and pieces, or in this case flush the whole system.

Jeroen

Did a full flush of the tank and clean up the sensor with blower and it has worked. The coolant is completely changed to new. So far the problem hasnt recurred yet.