How many coolant sensors?????

There should be a level sensor in the coolant top up bottle. It's 2 wires sitting in the level where the coolant should be, and they corrode up and give misleading level readings. The ECU thinks the level is low and flashes up the coolant light.

Carefully and gently scrape the wires with a small screwdriver and it should clear the problem.

Take the top off and you will see them.
Easy way round it is to overfil slightly, but only use G12 coolant.
Mine did it especially when cold in the mornings ie frost!
The overfill stopped it straight away.
Glynn

What year is your car?

Well, ETKA is showing the coolant bottle as having the connector fitted for the level sensor, and the part number for the bottle is the same as other models which do have the sensor fitted.

Can you see a part number on the bottle so I can cross reference it? Maybe someone put a non standard bottle on at some point and linked the wires with a resistor, and now that link is failing for some reason.

Look around the area for a loose plug which would clip onto the bottle and see if that's there. The sensor mount is in the top half of the bottle and enters the bottle at a 45deg angle.

It's a standard engine across the VAG range, and they all have the same coolant bottle and sensor system fitted. The plug should be somewhere close by to the connector and might've just fell off.

See, there's a fix some people used to do to prevent a known problem some time ago. The coolant bottles used to leak where the sensor is fitted into the bottle, and coolant used to weep out under pressure. The connector being clipped on with a watertight seal meant that the coolant had nowhere to go and used to creep down the wires and into the electrical system, and it went everywhere there was a wire to go down. Google "Coolant migration" if you want to find out more. People used to disconnect the plug and fit a certain resistor across the wires to fool the ecu into thinking the level was okay. With no plug connected there was no change of the electrics being filled with coolant. Maybe this was done at some point and the resistor is now failing.

get someone with VAGCOM to see if there is any error codes flagged up on the car. at least then it may give you an indication of what is the fault. you may also have a coolant sensor above the Oil filter housing have a look at all your water pipes and where they enter the engine block you have have a sensor there.

I don't have my Ibiza anymore so can't check, but I'm 99% sure mine didn't have a sensor in the coolant bottle either.

I'd suggest you need someone with vag-com to read off the exact faults that are being recorded. Clear the faults first so there's no others to mislead you, then trigger the faults/warning beeps as usual, then go back in with vag-com and read what faults are flagged up.

Could be a dodgy temperature sensor...

If there is no level sensor in the tank, then your car doesn't have coolant level sensing. The header tank is the only free surface in the cooling system so you can't put a level sensor anywhere else.

The only coolant sensor you have is the one you have already changed. It has two sensors in the one housing, one (G2) feeding the dashboard and a separate one (G62) feeding the ECU.

Flash+beeps is the dashboard warning of a coolant problem. Not necessarily level, just a problem, a reading out of spec.

If you see no faults with VAG-com, then the ECU must be seeing reliable data. Perhaps VAG-com doesn't test the sensor feeding the dashboard, just the one feeding the ECU?

One thing you might try is cleaning the connector to the sensor unit. Spray with electrical contact cleaner, plug and unplug several times to try to wipe the contact surfaces clean.

Otherwise it might be time for a new sensor assembly - but I'd like to know if VAG-com can detect faults in the G2 sensor, because that's where your faults most likely lie.