Flashing Coolant Warning On Startup - Coolant Levels Fine

[Yogi]

Hey All,

Just seeing if anyone has experienced a problem similar to me and what they did to fix it. I have a 2011 GTI DSG.

Since my last service 45k, I have started to get a flashing/beeping coolant light on startup first thing in the morning after a long drive (45 mins +) the day before. The MFD also displays "Check coolant level". Every time I open the bonnet and check the coolant level it is well above the minimum line, around where the middle of the reservoir is. To clear the problem I simply turn off the ignition and restart the engine and it goes away however it's quite nerve racking and frustrating that it happens ~ twice a week. I have even started checking the coolant level before starting the engine incase I can catch the level being low prior to starting the engine and the fault appearing. I have once checked the engine cold and the level was fine only to have the warning when I started the engine so I don't believe it's an issue with coolant expanding/contracting from below min to above after starting.

Have taken to VW dealership twice now for the problem and every time they have said there is no fault code when scanned so they don't know what the problem is. This is despite the tech saying when I dropped it off that is a common problem on these and R's (which he then incorrectly proceeded to tell me had the same engine) and is either the water pump or coolant reservoir.

My gut tells me the LLS probes inside the coolant reservoir are probability reading intermittently on startup or after startup the volume inside the reservoir increase slightly higher on the probes (still above min) where there is better conductivity but if this was the case why wouldn't they either replace the reservoir or top of the coolant up?

Any thoughts would be appreciated

Cheers.

[vdubmotorworx]

i think it was only tiguans but they used to have the same issue and that was due to the pipes expanding and pulling the coolant level below the mark. fix for that was a sticker placed on the bottle with new higher levels. not seen it on golf before. make sure your coolant is nice and reddy pink if not it might be too weak as on crafters it also comes on if the coolant to water mix is low. dont know if its the same on golf or not. try putting the coolant level up another 2cms and try it again. if still faulting i would replace the bottle.. it wont show a fault code as its just doing what it thinks it should... seeing a incorrect level... ...VDUB..

[Transporter]

Also, check the connector from the reservoir. The sensor may be faulty as well.

[Yogi]

Luckily enough it happened first thing again this morning, drove it straight to the dealer without switching it off so the fault was still on the MFD/Dash. Hopefully they drain the coolant and put in a new reservoir this time.

Thanks for the tips - the coolant isn't a real strong red colour more a washed out pink/red but the coolant has never been topped up with water by me, so unless the tech got his ratios wrong... The dealer is now using G13 coolant, not sure if this was used in the 45k service and it's causing the issue now. Did try disconnecting and reconnecting the sensor a few weeks back and all the contacts look fine, not build up on them.

Shall see how we go today...

[Yogi]

Service replaced the expansion tank (with sensor inside), part no. VW1L0121407A. Will see how it goes, fingers crossed.

[fonsii]

Service replaced the expansion tank (with sensor inside), part no. VW1L0121407A. Will see how it goes, fingers crossed.

Did the replacement of the expansion tank do the trick? I seem to be having a similar error to yours and VW couldn't figure out what's happening.

[The One]

Ive seen quite afew of the sensors go due to incorrect fill level @ services, what happens is the 'technician' fills up the coolant reservoir without regard to the min/max marks, 9 times out of 10 its filled above the max mark, then when the coolant 'expands' it sits higher then the sensor, then when the vehicle goes cold it looses pressure and goes back to an appropriate level, it usually does this over and over untill the sensor (which is integrated in the bottle) becomes 'contaminated' with coolant causing the sensor to constantly think it is over full. My 2 cents.

[Umai Naa!!]

The sensors in them are a bit hit-and-miss. It's the same setup they've been using for about 25 years now.

If you're savy, you can test the resistance of the sensor at varying water levels.

[Snail Style]

The sensor measures the conductivity/resistance of the fluid the two probes sit in. Having a overfilled bottle at a service won't effect it unless they have put too water in and the concentration has dropped.

Quite normal for the sensor to crap out on them, have heard of cleaning the with tooth brushes and also bending the probes closer(never seen that one done) to fix it.