P0128 TSB dilemma

[mtgjudge]

Hi folks!

I kind of new to the forums and I'm hoping someone can help me out. I'm an auto repair DIYer but I'm new to the whole Mazda thing. (The newest car I've worked on before this one was a 1994 Saturn.) I have a variety of specialty tools and own a workshop manual, but no formal training. So here's my problem:

For the past few months, my 2004 Mazda 3 has been giving me a P0128 trouble code (Coolant Temp Below Thermostat Regulating Temp).

I did some poking around and I found this thread:

http://www.coremazda.com/forums/maz...etins-tsb/264-mil-illumination-dtc-p0128.html

So, it seems there is a service bulletin saying there might be a PCM recalibration needed for my vehicle, and that it might be a "false" code.

I called the local Mazda dealer and they wanted $100 just to diagnose the vehicle (read: hook up an OBD II unit similar to the Actron that I own) and $150 to reprogram the PCm *if* that's what the problem is.

My questions are....

1) Is there any way to tell if my thermostat actually needs replacing? (seems like a dumb question, but in light of the TSB I am wondering)

2) Is it worth it just to buy a thermostat and put it in? Is it a PITA to do?

3) Should I bother with the Mazda dealer/PCM issue? It's not covered under warranty, they were so eager to point out...

Thank you VERY MUCH for your collective wisdom. I look forward to any advice you may have!

 

[TRXSandRacer02]

first, new thermostat is about $40, second, pcm update for that code is very old, about 5 calibrations since so yes you should take it in for that, and yes i sucks replacing the thermostats but is easier on a hoist since 2 bolts are easily accessable from the top and the others are easier from the bottom its up to you but for about 150 you shoudl be able to ahev every thign done, i have seen thermostats stick and fry these engines BEWARE!!!!