But the light still pings on in the morning. After 5 mins driving and restarting the motor the light then goes out.

I used the correct coolant to top up, but it does not seem to have worked.

Any tips ?

You're probably the several thousandth person to have suffered from the dreaded "dirty prongs" error.

On a cold engine, open the expansion bottle, and look for two metal prongs sticking down into the coolant. Scrape these a few times with a flat blade screwdriver. This should cure your false positive warning light.

+1 wot he said ^

I get it occasionally and that has always worked. The muck is just breaking the electrical signal the sensor needs.

Edited 5 June, 201313 yr by Aspman