yelcab2

I have a Launch X431 Pros Mini which is quite powerful and feature-rich. It just recoded the new DI injectors on a 2014 BMW 325i.
It has only one Diagnostic code: BMW 002EF4 which translates to P0128 in OBD2 language. The "Help" function on the Launch actually spells out

1. Check wiring for short to ground
2. Replace Thermostat.

It also confirms that this code reduces warmth in cabin and that is what I am seeing with zero heat.

I have replaced the thermostat twice in the last 6 months with the second one being the expensive BMW brand
I have replaced both temperature sensors with expensive BMW branded ones.

seanjordan20

Were you getting the code each time you replaced the thermostat or are you trying to figure out why you don't have heat.

yelcab2

I replaced the water pump, thermostat and the sensors 6 months ago (all BMW), and the code went away until a few weeks ago when the Service Engine Soon light came back. I read the code and it was P0128, so I replace the engine coolant temp sensor (on engine, not on radiator) again with a BMW one, the code returned. I replaced the air filter and the code remains. I happened to notice that I got no heat (because it is not winter and I sometimes need heat). So, according to the Launch Help description, the code leads to no cabin heat. Also, I need a clear OBD2 scan in order to pass Smog in California.

So I need to really solve this issue.

It still could be the BMW thermostat that is only 6 months old. That seems too short a life for a BMW part.

seanjordan20

I just had to read your old thread. At this point I'm thinking it's the harness itself that's causing the issue. No way these thermos and sensor are going bad by themselves or having this issue so quickly.

yelcab2

I did an oil change yesterday so I had access to the 2 pin connector for the Thermostat. While engine is off, I measured the resistance of the two wires. One wire is brown, and that is solid ground. The other is high impedance and is probably pulled to 12V when the thermostat is supposed to be heated up.

I think it is ... OK.