2009, 75k, A wall o' text:

3 months ago: Thermostat warning came on “yellow” twice. I took it to the mechanic (so drove it 10 miles after the first light came on), who said I had a leaking thermostat and replaced it. Driving it to work the next day, the thermostat warning came on “red”. I immediately pulled over and had the car towed. The mechanic called, said they had not replaced the thermostat cap correctly (duh!). They checked my coolant levels, put the cap on and sent me on my way.

2 months ago: Went for an oil change and the attendant said he smelled gas (yikes!). Had the car towed to the mechanic (not the same one as before, for sure) and they said a hose was starting to rub up against something and had a very small leak. Replaced the hose.

1 month ago: Chemical smell with the blowers on, goes away with A/C and/or recirculated air going. Brought it back to the second mechanic who said that my cover gasket (I think) was leaking oil and needed to be replaced. Replaced that part, and all was good for two weeks. They mentioned that my water pump was going to need to be replaced shortly, but that I could a couple of weeks.

2 weeks ago: Melting chemical smell with the blowers on, goes away with A/C and/or recirculated air going. Brought it back to the second mechanic who said that the first thermostat was faulty and leaking coolant all over the place, was almost empty. We replaced both this and the water pump. A strong mildew smell has been present since then, but I ran the heaters on full blast for a while and it seemed to dissipate.

Today: Drove to work with the air off (it’s lovely out!). Rolled up the windows, turned off the car, and got a huge PUFF of melting plastic. When I turned the car off, the fan under the hood turned off as well. I went around the car to lift the hood, and the fan turned back on for ~5 minutes (the keys were in my hand so the car was definitely off). I gave the car about 10 minutes after the fan shut off and drove it to the first floor of the parking garage so the tow truck could get to it easily. No lights came on, no fan, no smell.

It’s now back at the mechanic, and I’m waiting to hear. From Google-fu, it looks like a sensor issue but I don’t know if that would account for the plastic smell? My instinct is to have the mechanic do what they need to do to fix it, then keep/drive it a couple days to be doubly-sure.

All of this work is under warranty (either the car’s or the part’s), so it’s less about expense and more about the hassle of having to go back and forth to the mechanic.

Anyone have any similar experiences? I’m thinking about renting it out as hands-on “Diagnosing That Weird Car Smell” training :P

FWIW, the only other work I’ve had done on this car was the timing chain about a year ago.