Your explanation makes sense Callisto. I would think this repair fixes it for good since there is no longer a thermostat to fail. I wonder if this compromises the coolant control valve but I don't really care at this point. I've got the warranty extension and a service contract for whatever that's worth. I had a chance to inspect the work and I do have to say this tech really did a great job. No mess anywhere. I'm done.

 

It does not and will not compromise the coolant control valve. In my own Mazda I replaced the OEM thermostat with a specialized adaptation of a STANT thermostat and modified thermostat housing . I also by-passed what is often miss described as the transmission cooler when its true function is actually to bring the transmission fluid to operating temperatures at or equal the engine oil. During cold starts . I never liked my trans fluid running as hot as the engine oil.
I have had a few customers with HVAC Mazda system issues most were directly caused from not doing a coolant change much sooner than Mazda recommended.
reading this thread again I am more to support that the ECU "flash" with the new calibration was more to cure your issue the hard part service. But no verified evidence to support one way or the other.
I should also mention that dealerships (they are independently owned) often use the descriptive identifying service employees as "Tech". There are in reality very few dealerships that go to the trouble of actually have a Mazda certified auto mechanic or independent certified mechanic and even better a Certified Automotive Diagnostic Technician employed. Dealerships are NOT required to have any either. So just an FYI when describing whom may be working on and diagnosing issues on your Mazda.
We actually have a Mazda factory trained mechanic here that may also verify this little bit of info.

I have an employee in the service shop that only job is to keep the shop clean all day and his title is "Tech". LOL Its perfect when everyone but he is on lunch and customer comes in and is in a hurry.... I just tell them I only have 1 Tech right now and he is busy you will have to wait a little bit. LOL

 

This is interesting, but also concerning. As I reported in a separate thread recently, I also have low temperature on my 2022, though not as low as in this case. Mine didn’t trigger the code and, naturally, the dealer wouldn’t proceed. From what is described here, it seems that the coolant control system is liable to malfunctioning. In my case, I’m concerned that the engine never gets up to proper operating temperature—plus I have no idea what this means for other systems that require temperature regulation. I wish Mazda would sort this out.

 

You are not reading clearly or not understanding the information I posted.

Here in simple terms if your engine did not get to normal operating tempreture yet the ECU would post several related DTC and you would smell gas from the enrichment during cold start because your engine would never go into closed loop operations . And it is very like
Your ECU would place the engine in protective mode other wise called “Limp mode operation” .

 

The dealer won't correct the issue until a tech or the ECM determines it isn't in spec. When I monitored mine as new it typically ran 185F-195F when fully warmed up. Once I noticed the gauge not settling to the usual zone I scanned again and saw it was running 159F-178F when warmed up. No code for a while - maybe weeks and a thousand miles later the light popped with P0126. They replaced the CCV and it went back to normal 185-195F when warm. On this reoccurrence I saw the same thing, scanned, and saw the same 165F-180Fish temps and never higher. It was a couple weeks later and the light popped again. After the most recent repair things are back to 185-195F. Only time will tell if removing the thermostat and installing the dummy plug and reprogramming the ECM corrects it for good. You can always have a mazda dealer check the car and repair a condition outside the program if applicable but as my dealer always says, no code, no noise, no issue. Although we can see it is different and know the eventual outcome you just have to be patient and wait until those techs come drooling over the finish line.

 

Temperatures must become confirmed manually not always relying on the sender that reports to the ECU and retrieved by a scanning device at the OBDII diagnostic connector!

 

Yup that's basically how it works. It is great of Mazda to at least acknowledge the issue and create a program though. Not all mfg will admit it when there is a widespread defect.

 

My dealer took good care of it. It's a bit embarrassing for them since they have to do what mazda says and the first repair didn't fix the issue. They offered a loaner, did the work pretty quickly, and were friendly the whole way. I've never had a service issue at my mazda dealer it seems well managed. I wish we could get it taken care of when it first manifests but I get they need the code to prove to mazda and avoid a debit.

 

Thanks campb292. That’s exactly where I am. I just have to wait for the code. While I have no knowledge of the whole coolant system, i.e., what else is temperature-regulated, I wonder if there are any long-term consequences of low and fluctuating coolant temperature, even if it doesn’t trigger a code? I certainly don’t want to pay the dealer for the warranty fix when I’m not sure that’s the source of the problem. It’s an annoyance.

 

You do not necessarily need to wait for the DTC(code) it already may be activated and not yet by the check engine light. If you are concerned you should have your ECU checked in the 3 main areas' as well have the "experienced" person look at any and all of the ECU ,DTCs current and pending and the historical counters.