I have an Audi 2005.5 model A4 3.0 Quattro with approx 71,000 miles. I noticed a month ago during a 300 mile drive that my temperature gauge was not rising above the ¼ mark. I pulled over at a rest area, turned off the car and spoke with a mechanic who suggested I take it to the dealership. When I turned the car on, the temp went to the mid point and remained there since I noticed it happening again this week. I’m trying to figure out what the problem could be and what costs I might incur to have this fixed. I know that at the 90-100K mark I’d have to replace the timing belt, but given this problem I’m wondering if I should get this fixed or if I can wait since know warning lights (temp or engine) are coming on and the temp is on the cold side so there’s no threat of overheating (I hope). I also wonder if it is ok to still drive the car until I get this fixed. So far I’m thinking I either need a new thermostat or temp sensor, but still am wondering as to the costs and whether or not these can be the actual problem.

Thanks,
CJ