e6t.lab.rat

I was forced to replace my thermo because my smog check and registration due date was nearing and the CEL didn't go away. So I replaced thermo, cleared CEL with my code reader and tried to have my smog done. Unbeknownst to me when I cleared the codes it cleared everything from errors to drive cycles. Without the drive cycles my vehicle could not pass smog test. I had to drive and add about 30+ more miles so the computer could establish drive cycles. Went back to complete smog and passed, I could finally register my car.

After some driving your computer determined that the drive cycles on the thermo were all in sync or, operating normally so it turned of the CEL. I had this on/off CEL a few times with my old thermo then finally it just didn't turn off. Hopefully yours stays off.

Quarta2six

Understood... I'll change the sensor when it comes since that won't hurt. If I get the CEL again and the code is the same. I'll just change the thermo once again. I appreciate all the help bruh.

Quarta2six

CEL is back with the same code, P0128. Ive changed thermo and temo sensor. Could the new thermostat be bad? Does it have anything to do with the cold? I really dont know whats the problem. I have an emissions test before the end of the month. My only option would be to replace the thermostat again. I've only replaced it once for anyone reading this thread and gets confused. Any suggestions?

tonyb635

How are you reading the stored code? Sometimes there are more clues in there as to what could be going on. I personally hate throwing parts at something because my luck it doesn't work or it's the last thing that I fixed. After adding up these costs sometimes it's better to have a pro at least look at it.

Quarta2six

I've gotten it read before changing it a couple different times since it was going off and coming back on. When I did take it to my mechanic and he hooked it up using his computer is said Thermostat stuck open. He had cleared the code and I had replaced the thermo. Then I had got the code again. So im sure it says the samething, not many options with this code. Crazy thing is it turns off by itself sometime. I posted this thread today when got in the car to drive home from work the damn CEL is gone. Im starting to think it has something to do with the weather being so cold..... Im going to take it to the emission station first thing in the morning so i can pass the test. then im just going to order a new thermo and temp sensor. Since the light went out, does the fault have to be completely removed or will I pass since the light is off and functioning properly now. Jus curious if past memory has anything to do with it....

balbs

I would clear it right before you take the test. From what I've heard (could be wrong) the CEL would pop up if the error is sensed after 20 or so times depending on the fault.
I don't know about the east coast, but here in California it's basically a visual inspection. If they don't see a CEL, that's a check off the list and move on to the next part of the test.

e6t.lab.rat

Could be a bad connection at the thermostat. Is the replacement thermostat an OEM brand, Wahler? I ask because I ordered my first thermostat off ebay assuming it was OEM and boy was I misled. BIG MISTAKE! and lesson learned (for the most part ebay can be a good place to buy things, you just need to be a little more cautious of what you're purchasing, caveat emptor!). The part from ebay didn't last for six months. When I went to unplug my thermostat the connector INSIDE the thermostat popped right out along with the OEM clip! There was so much corrosion that the leads inside disintegrated. Thank God I still had my old thermostat. I got my refund back less shipping.

That CEL P0128 code turning on and off sounds like a bad connection somewhere, an open and closed circuit repeatedly. It could possibly be a bad thermo again if it's not OEM.

Quarta2six

Yea I'm starting to think its a bad connection also... I got the thermo from the dealer but when I order the new one Im going to get it from ECS they sell the genuine BMW along with the Wahler brand so Im going to go with Wahler. How could I check the connection besides a visual inspection at the thermo. I'll try and see if I can trace any wires but Idk if I'll find anything its worth a try tho for sure. The dealer sells remanufactured thermo's, for some reason i don't like reman. parts something about it doesn't sit with me but at that time I had no choice couldn't wait on shipping. ECS has the BMW OEM for half the price the wahler is about a $1 more.