Today on the way home from work my check engine came on. Its the first time I've seen it since owning the car 86k on the clock. It says increased emisions,I know it can be a number of things wrong. Until I can get to my mechanic to get it read am I ok driving the car? Im not sure if any damage can be done. My mechanic is on vacation for the next 2 wks so can I wait or can I get it read and a parts store like most other cars. Im not going to the dealer and he does all my work. Just my luck... Thanks all help appreciated?

 

I would at least find someone that can read the codes to see if it's okay for you to wait or how bad it is. 2 weeks is a gamble to drive the car around if you're unsure.

 

Go to autozone they can check it for you free get the code and google it.
I also had SES first time a few wheeks back. Mine luckily disappeared on its own.

 

If the car is driving normally you could wait. Like Margal said, go the AZ and have them read it just so you know.

 

Possibly a bad thermostat? Search for the method of accessing your coolant temperature through the diagnostic function on the dash and monitor your temps. You should be at around 99-105C when fully warmed. Anything above or below that is definitely the thermostat causing the error...

 

Most likely your O2 sensor, fault code will tell you of course for sure, but at that mileage E60 sensors will start to act up, mine has been telling me this for a few months now, just received it and am in process of installing it any day now.......

 

Ok fellas so I went to Pepboys this morning got back code P0128. From searching online seems as though its my thermostat. Can anyone confirm that's what it is before I go but one and put it in? Also once I put it in can I wait till monday to clear the code because that will be the only time I can get it done. I've had places where I dont know anyone tell me they cant clear it for legal reasons I guess....

 

Go on Amazon and get one anywhere from $25 to $50 for cheap ones . Then you can keep it in your car and use it when needed and also clear codes . Better yet get the OBD cable and download inpa for BMW's then you can code your car also . You can get the thermostat from ROCK auto for pretty cheap. Good Luck

 

Just had that code on my 05 545 recently (2 weeks ago). I replaced my thermostat, and no SES light since. I drove the car for a few days thinking the code will just clear itself but never happened. So I cleared it myself with my Code reader. All is good now, that is until my expansion tank fails lol

 

Sometimes a burned out thermostat heater coil will generate a P0128. Also many other things it could be, but this one is easy to check.

Pull the harness connector off the thermostat and measure the resistance between the two contacts on the thermostat. Should be around 16ohms. If it measures 1 that means and open circuit (infinite resistance) and the coil is gone.

Coil is designed to help the thermostat open faster under heavy engine load and if the coil is burned out it really won't hurt anything (or affect emissions) but the light is annoying. Thermostat must be replaced.