[BayMoWe335]

Hey guys. Service Engine Soon light came on in the 335i (13,000 miles) and I took it in immediately.

Sidenote I asked them to look in to: I had noticed the heater was not working well AT ALL. Almost felt like the air was blowing cool on 84 degrees.

The called me and told me the thermostat was bad and replaced it. They said that was probably causing the heater to run poorly too.

1) The SES comes on for a thermostat? What is the thermostat's purpose? I am assuming it's the thermostat for the engine, not the AC/heather system, correct?

2) Why did my thermostat go bad already?

3) Is it true a bad thermostat can cause the heater to not work well?

Thanks. Gotta check these stealership guys out..

[BayMoWe335]

Got the car back...heater feels better and no other issues. I guess the thermostat does affect the heater.

[queensfield]

Yes, thermostat fails in the open position, which does not let the engine get to its operating temperature. This will cause no heating in the cabin and falling mpg since engine is not running at its optimum operating temperature. I am surprised that yours failed so early since you have a 2010.

[BayMoWe335]

Originally Posted by queensfield

Yes, thermostat fails in the open position, which does not let the engine get to its operating temperature. This will cause no heating in the cabin and falling mpg since engine is not running at its optimum operating temperature. I am surprised that yours failed so early since you have a 2010.

Just a fluke?