2019 CX-5, Coolant problem (CEL = P0126 )

Hey guys,

Hoping someone could possibly chime in. I got rear ended about a month ago and it required my entire liftgate to be replaced. Since getting my car back, I had to go back to the place that fixed it because one of the tail light bulbs burnt out.
Now, Today, I was driving home from work and got the check engine light. I retrieved the code, which was P0126. has anyone else gotten this code?
On the highway my car seems to be running rather cold (160F).

I noticed Mazda released a Service alert for 2018-2020 Mazda6 (non-turbo), and 2018-2020 CX-5 (non-turbo) for : 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'm experiencing two of those symptoms.

Unfortunately, My car is at 40,000 miles. Just over the 36k mark.

Really don't want to have to pay for a repair like this....Any help or advise is appreciated.. Thank you
 
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2020 CX-5 AWD
The suggested repair from Mazda is to replace the thermostat. They may be covering this repair as a systemic issue, so you might want to ask your dealership what their current policy on this TSB is. Not much of an expense for them to keep a few of their customers happy, and I can't imagine why they wouldn't just go ahead and give extended coverage for this one. But I've been surprised by various automakers denying coverage for stuff like this in the past, so I wouldn't say it's a done deal just yet.
 
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2014 Mazda3 S GT auto, 2008 MX5 6-speed
You have 40,000 miles in 2 years? Now that's a lot of driving. My 2008 MX5 thermostat stuck closed at about the 47,000 mile mark. It was about 7 years old at the time.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Hey guys,

Hoping someone could possibly chime in. I got rear ended about a month ago and it required my entire liftgate to be replaced. Since getting my car back, I had to go back to the place that fixed it because one of the tail light bulbs burnt out.
Now, Today, I was driving home from work and got the check engine light. I retrieved the code, which was P0126. has anyone else gotten this code?
On the highway my car seems to be running rather cold (160F).

I noticed Mazda released a Service alert for 2018-2020 Mazda6 (non-turbo), and 2018-2020 CX-5 (non-turbo) for : 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'm experiencing two of those symptoms.

Unfortunately, My car is at 40,000 miles. Just over the 36k mark.

Really don't want to have to pay for a repair like this....Any help or advise is appreciated.. Thank you
You don’t have to pay for this repair as thermostat and gaskets are covered under 5-year / 60,000-mile powertrain warranty. Just take your 2018 CX-5 with a copy of TSB to your Mazda dealer for warranty service.

46E9A65C-31E2-4C90-8AE4-A73E46824D1A.jpeg
 
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2020 CX-5 AWD
You don’t have to pay for this repair as thermostat and gaskets are covered under 5-year / 60,000-mile powertrain warranty. …
So now I'll enter my guilty plea for not looking at the items covered under the power train warranty 😔

Being a DIYer, I'm not personally at all concerned about stuff like the thermostat, and also just assumed Mazda was like most other automakers with respect to what their powertrain warranty covers. So I was quite surprised to see the t-stat and the pumps on the warranty list, and hats off to Mazda for including these items. Another reminder to never assume anything. And thanks for posting this, which hopefully the op will come back and read.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
So now I'll enter my guilty plea for not looking at the items covered under the power train warranty 😔

Being a DIYer, I'm not personally at all concerned about stuff like the thermostat, and also just assumed Mazda was like most other automakers with respect to what their powertrain warranty covers. So I was quite surprised to see the t-stat and the pumps on the warranty list, and hats off to Mazda for including these items. Another reminder to never assume anything. And thanks for posting this, which hopefully the op will come back and read.
Not just Mazda, I believe a typical powertrain warranty will cover thermostat and water pump, part of engine components.
 
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2020 CX-5 AWD
Not just Mazda, I believe a typical powertrain warranty will cover thermostat and water pump, part of engine components.
I've spent most of my time during the past few years in the world of Kia/Hyundai, and can say for certain that their powertrain warranty does not include what Mazda does. The water pump is covered, but virtually nothing else external on the engine. And these automakers have even denied coverage of the transmission temp sensor, which is located INSIDE of the tranny case. I've also, worked on other make family vehicles but those were higher mileage, so I rarely (if ever) checked those warranties.

But again, this subject is not important to me at all, and I have no interest in doing any additional research. I'm certainly willing to accept what you said about the warranty of most other automakers, and just leave it at that.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I've spent most of my time during the past few years in the world of Kia/Hyundai, and can say for certain that their powertrain warranty does not include what Mazda does. The water pump is covered, but virtually nothing else external on the engine. And these automakers have even denied coverage of the transmission temp sensor, which is located INSIDE of the tranny case. I've also, worked on other make family vehicles but those were higher mileage, so I rarely (if ever) checked those warranties.

But again, this subject is not important to me at all, and I have no interest in doing any additional research. I'm certainly willing to accept what you said about the warranty of most other automakers, and just leave it at that.
Although never interested in getting a Hyundai or Kia, but I‘ve always been having the impression that Hyundai and Kia are having the “America’s best warranty”. Started with 10-year / 100,000-mile bumper-to-bumper warranty when they just got into the US market, now it’s 5-year / 60,000-mile bumper-to-bumper, 10-year / 100,000-mile powertrain warranty. If a coverage period of a new-car warranty is the same as Mazda’s powertrain warranty for 5 years or 60,000 miles, I’d still say it’s a better warranty no matter what.

Of course YMMV, we have to read the fine print to realize if there’s a catch somewhere. Our problematic belt tensioner on CX-5 is not covered under powertrain warranty, which was a surprise to me when I first learned that after I found mine is leaking at 40,000 miles.
 
well.. looks like they're not willing to cover it because it's the "coolant control valve" that's causing the thermostat to stay open...

Pretty pissed right now.

My car literally had 39,500 miles on it when this problem occurred.

Coolant control valve seems to be electronic.. really starting to think the repair done on liftgate could be affecting this.

1 day after my liftgate was repaired, rear tail light burnt out, and the lights flickers inside my car at a separate time, but just after the fix.

edit: Part is also backordered until Late february, even though I can easily find it online, but if I/they get it from a third party retailer, there is no warranty on the repair...
 
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2014 mazda cx-5 touring FWD
Where is this" coolant control valve" valve located.I've never heard of it.Is the dealer or Mazda just blowing smoke?Anybody?
 
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2020 CX-5 AWD
well.. looks like they're not willing to cover it because it's the "coolant control valve" that's causing the thermostat to stay open...
They are probably 'diagnosing' by reading the TSB, which says to replace the valve you posted above. And that part (PYFD1516Z) will probably have a stealership billing somewhere around $400, plus another $200-300 for labor.

I was puzzled how an electronic valve could be 'causing' a mechanical thermostat to stay open, and went looking for documentation about this valve in the FSM. I have so far been unable to find any functional description, and very few references of any kind to it either. Could be I'm just missing it, so I'll continue to search.

That said, if this problem shows up on either our 2019 or 2020 CX-5, I would most certainly remove and test the thermostat (which is integrated into that much larger water control valve), before giving any consideration at all to replacing that very expensive valve.

I've found in a number of prior instances with other vehicles, that the automakers seem to take the easy, simple approach (for them), and just specify replacing an expensive part, instead of the more owner-friendly idea of trying to diagnose the actual issue. And it's certainly possible for that to be the case on this one as well.
 
I'm tempted to just buy a thermostat online for $10 and replacing it myself to see if it fixes the issue..

I just can't seem to wrap my head around how a thermostat like this fails? As you said, it's a mechanical piece.. :/
 
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2020 CX-5 AWD
… I just can't seem to wrap my head around how a thermostat like this fails? ...
Actually lots of thermostats fail, and it's not unusual at all for that to happen. The real question here is that Mazda is saying that the water control valve is keeping the thermostat open, and that's what I'm not understanding. Perhaps there is documentation available which explains exactly how this valve can control the thermostat, but I have not found anything yet.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
As a "last resort", I would suggest going over the dealership's head and contacting Mazda Corporate yourself to file a complaint and open a case. You're not that far out of warranty, and with the information provided, they may just goodwill the repair. Not something I would bank on, but it's possible. Good luck!
 
As a "last resort", I would suggest going over the dealership's head and contacting Mazda Corporate yourself to file a complaint and open a case. You're not that far out of warranty, and with the information provided, they may just goodwill the repair. Not something I would bank on, but it's possible. Good luck!
certainly trying this. The dealership was giving me s*** because I maintained the car myself up to this point. Explaining to me that there is a relationship built when maintaining with the dealership. Mother Fker, the relationship is that I bought this car brand NEW from you. I ain't paying $150 for your simple ass oil change, so that you will have my back in cases of out of warranty repairs.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
well.. looks like they're not willing to cover it because it's the "coolant control valve" that's causing the thermostat to stay open...

Pretty pissed right now.

My car literally had 39,500 miles on it when this problem occurred.

Coolant control valve seems to be electronic.. really starting to think the repair done on liftgate could be affecting this.

1 day after my liftgate was repaired, rear tail light burnt out, and the lights flickers inside my car at a separate time, but just after the fix.

edit: Part is also backordered until Late february, even though I can easily find it online, but if I/they get it from a third party retailer, there is no warranty on the repair...
This so called “engine coolant control valve” mentioned in the TSB is the “electrical thermostat” been implemented on the 2.5L along with newly added cylinder deactivation since 2018 CX-5. It’s served as the old mechanical thermostat functional wise for better control and efficiency. Unfortunately it also becomes a first-year problem just like the EPB on 2016 CX-5.

You should call MNAO directly and tell them this new engine coolant control valve should be covered like old mechanical thermostat under powertrain warranty, no ifs or buts.

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