Noticed my Mazda 3 2020 has been running cold lately. Is this an issue? Outside temps will be 40° F - 50° F.
Picture shown was taken on highway after driving for 1.3 hours.
Ice cold zoom zoom
Thermostat could be stuck in the open position. P0126 fault code. There is TSB for this.
That’s not cold Doc. One look was all I needed. That’s normal operating temperature.
Mazda would disgaree with you. They even issued a TSB over this and will replace the faulty part if you are in warranty
Better than overhearing I’d assume ha
This happened to me and I live in a cold place so basically it meant I was getting no hot air in the cabin. The dealer replaced everything for free and said mazda is aware of the problem. I had the same vehicle as you by the way. Also make sure you check your coolant level after the repairs are done. It may be significantly lower than normal.
Your going to need a OBD code reader diagnostic tool , it’s a device that you hook up to vehicles OBD port. It communicates with the vehicles computer. Go to AutoZone, they will scan the code for free.
A failed thermostat is a mechanical device so not sure obd will see the issue.
Your thermostat has failed. They fail open, which is why you car is running colder than it should
Just a thought, why having your engine run colder isn’t better? Usually the less heat the better longevity.
Do they even use thermostats anymore? It’s probably some overly complicated electronically controlled valve that will be super expensive to replace because a simple wax-filled cylinder that has worked fine for the last 100 years isn’t precise enough to accommodate today’s emissions regulations.
Thats exactly what it is. Its a $350+ part. Not terribly expensive or hard to replace but still
This is directly MGSS Mazda Service Global Support: Some customers may experience the check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: The engine takes longer to warm up The engine temperature gauge fluctuates The low coolant temperature indicator (blue) light stays on longer or comes on while driving Poor heater performance, especially at idle
I called just called the dealerI called just called the dealership and they said since there’s no engine light on they won’t replace it since it doesn’t meet the terms of the TSB.
My Mazda was running cold when the thermostat was slowly failing. You can probably expect a check engine light pretty soon, but i wouldn’t wait on it, especially if you live in an extremely cold area. A cold engine is very bad for the duration of its life because of accelerated wear and whatnot.
Brought it to the shop and they said they were literally “unable to look at it without the engine light”. I straight up asked for them to take a look at it directly and I would pay for all labor out of pocket but they said they couldn’t take my money without an engine light per Mazda’s Mx rules.
This post scared me as it doesn’t say what is actually normal. Normal warmed up is right in the middle. My '21 turbo is normal thankfully.
Coolant control valve If you have powertrain warranty, it’s covered
This is sort of a known issue for all non-turbo 2019-2022 model years for Mazda3 (talking here about US market).
Mazda doesn’t use a mechanical thermostat but an electronic one called Coolant Control Valve (CCV) and in the issued TSB (that got several revisions) they mentioned the problem is within the CCV with the fail-safe thermostat which seems to be opening too soon (some folks opened the CCV and manually adjusted that fail-safe thermostat and seems that the problem got fixed for them).
Personally I had this CCV replaced twice under warranty and issue wasn’t fixed and ended up being unsure on the root cause with dealers ended up being out of ideas and with open case with Mazda.
What is known now is that turbo engines never used CCV and from MY2023 they moved back to a classic thermostat and seems to have abandoned the CCV idea completely.
- 2019-2022 model has the part (15-16Z)
- 2023 model has 15-17Z which is listed as “Outlet, Water” and there is also a part called “Cover, Thermostat”
I wonder if that’s a deal with most or all their cars with the 2.5L I4 because I noticed something like that on the CX30 I rented but a smidge warmer maybe?
Its the coolant control valve, i just got it fixed under warranty on my 2021 cx5. Mine used to run cold all the time until it got replaced now it runs rock solid just below 210 F.