The temperature guauge on my hyundai elantra stays on cold after 10 minutes of idle, when I start driving, it stays on cold for about another 5 minutes then goes to normal. Then it instantly goes back to cold for a couple of minutes. Then it fluctuates from normal to cold. When I check the hoses, they are hot and hard to squeeze, what could be the problem?

. Check the connector to the temperature sending unit. Clean contacts and spray with WD-40.

. Replace the temperature sending unit, if the problem persists.

Or faulty thermostat.