New to the community...Thermostat issue (2020 CX-5 with code PO126)

Hello all, New the community.......
Simple question- I am stumped--- have a 2020 Mazda CX-5 with code PO126-- thermostat--- dealer wanted 1500 to fix this?! I am unsure of the location of the thermostat--- there seems to be security type star bit screws around where I believe it to be but dont want to start wrenching until I am sure of the location- it is an AWD 2.5 gas engine. Sorry for the seemingly simple question, but the vehicle isnt mine and I dont want to do something harmful to their car...... You Tube usually is spot on, but not so much in this instance on a 2020?!?!
 
See my corrected answer. Found a TSB....dealer should fix for free.
 
Be prepared for the dealer to ask you to pay out of pocket. The last page of the TSB states that the repair is covered for vehicles that are eligible for warranty repair. At 66k miles it sounds like you're just out of warranty, so the dealer doesn't have to cover anything.

With that being said, there are some good dealers out there who may go to bat for you. Your chances are improved if you can provide proof of regular maintenance done on the car, following the maintenance schedule in the Owner's Manual. Receipts for parts/services are a must. And treating everyone you come across with respect can go a long way. By being respectful and polite, but firm and calm, you'll be taken more seriously, and the person(s) you're dealing with will be more accommodating (compared to someone who is aggressive and arrogant out of the gate).

Good luck!
 
Good advice. And, I assume you are taking the vehicle back to where it was purchased. If unsuccessful, again, find a good independent shop who will probably repair for a lot less than that $1500 outrageous quote. This subject was discussed a couple years ago on this forum.....see attached link. Note in one of the posts the cost should be in the $6-700 range. Note the TSB states 1.3 hours labor to fix. Good luck and let us know how you made out to help other members.


 
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... there seems to be security type star bit screws around where I believe it to be but dont want to start wrenching until I am sure of the location....
If you (and the owner of the vehicle) are up for exploring a potential DIY fix for this issue, post back and I'll provide the details.
 
I'm all ears Edmaz !!!! Thank you--- was wondering if I am going to have to get a new plastic housing for the thermostat as well?
Much appreciated!
 
Be prepared for the dealer to ask you to pay out of pocket. The last page of the TSB states that the repair is covered for vehicles that are eligible for warranty repair. At 66k miles it sounds like you're just out of warranty, so the dealer doesn't have to cover anything.

With that being said, there are some good dealers out there who may go to bat for you. Your chances are improved if you can provide proof of regular maintenance done on the car, following the maintenance schedule in the Owner's Manual. Receipts for parts/services are a must. And treating everyone you come across with respect can go a long way. By being respectful and polite, but firm and calm, you'll be taken more seriously, and the person(s) you're dealing with will be more accommodating (compared to someone who is aggressive and arrogant out of the gate).

Good luck!
Great advice sm1ke !!! much appreciated!!
 
If dealer is unwilling to lower the price, you should consider getting an independent shop to fix it and bring the TSB with you. All the parts add up to be about $500 if not on back-order.
Thank you ceric - so this diagram link doesn't show a traditional thermostat right?
Definitely interested if you have this available!!!
If you (and the owner of the vehicle) are up for exploring a potential DIY fix for this issue, post back and I'll provide the details.
 
-- was wondering if I am going to have to get a new plastic housing for the thermostat as well? ...
First, just an FIY that. that plastic housing actually contains a computer-controlled coolant control valve. It's a 4-way valve, electronically operated, and is used in place of the simple mechanical thermostat that we're all familiar with. With the exception of the removable ECT sensor, the entire unit gets replaced, and they're currently running around $450. They're also in VERY short supply on the retail market.

Now having said all of that, there actually is a mechanical thermostat contained inside of the housing, which is supposed to function as a 'failsafe', that opens only on an overheat condition (i.e. at 105C). And it's the functionality of this mechanical thermostat which, according to Mazda, has some type of defect.
Although I've examined the original control valve, I haven't seen the new replacement part, and don't know exactly what they did to correct the slow-heat issue which is causing the P0126 to be set. So the standard repair is to simply replace the complete coolant valve with the new part, as stated in the TSB.

Now on another forum, I've participated in a really long thread, where lots of information was exchanged about this same issue. And one of the most interesting things came from a guy in Europe who claims to have successfully modified the mechanical thermostat, and resolved the slow warmup problem. So naturally I have to add a disclaimer that I've never actually tried this myself, and cannot confirm that it actually does work as he said it did. However, this is IMO a zero risk thing to try, simply because a replacement coolant valve would also contain a new mechanical thermostat, so the fall back if this doesn't work is going to be to replace it anyway. I can say for certain that I'll try this mod myself, if this P0126 ever shows up in either of our vehicles.

So having explained what the deal with this is, if you want to give it a go, you'll need to remove the mechanical thermostat from the coolant control valve and test it to see at what temperature it's opening. The guy who did this said that his thermostat was opening at 60-70C, instead of the specified 105C. So if the thermostat on this vehicle is also opening way too soon, then it would be a candidate for the same physical mod that he did - very simple and easy BTW.

To get access to the thermostat, all you need to do is undo the 4 Torx bolts on the part of the valve that's closest to the front of the vehicle. Although I don't think much coolant will spill out with the system pressure relieved, you might want to drain a bit of coolant out of the rad, just in case. Once you have that front cap+hose detached from the coolant valve, you'll see the thermostat in the housing, as shown in the first picture below, from the one I disassembled previously. Then all you have to do is simply pull it out of the valve, and separate if from the plastic housing that you can see in the second picture below.

Once it's out and separated from the plastic housing, just give it the standard hot water test, and find out at what temperature it's opening. Post back if it's opening early, and you want to try the modification.

And also an FYI that I've tried a number of different ways to contact KIRPART, who is the manufacturer of the mechanical thermostat. They've never responded to any of my inquiries, and apparently could care less if anyone is having problems with one of their products.

IMG_2740.JPG


IMG_2746.JPG
 
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Now on another forum, I've participated in a really long thread, where lots of information was exchanged about this same issue. And one of the most interesting things came from a guy in Europe who claims to have successfully modified the mechanical thermostat, and resolved the slow warmup problem.
Would you mind to post the link of that long discussion?
 
Would you mind to post the link of that long discussion?
I didn't think anyone would want to wade through all of the meandering stuff in that thread, but anyway <here> it is for your reading pleasure. Fortunately, the stuff I mentioned about the guy from Europe (Majkl) doing the mod is right at the end of it.
 
First, just an FIY that. that plastic housing actually contains a computer-controlled coolant control valve. It's a 4-way valve, electronically operated, and is used in place of the simple mechanical thermostat that we're all familiar with. With the exception of the removable ECT sensor, the entire unit gets replaced, and they're currently running around $450. They're also in VERY short supply on the retail market.

Now having said all of that, there actually is a mechanical thermostat contained inside of the housing, which is supposed to function as a 'failsafe', that opens only on an overheat condition (i.e. at 105C). And it's the functionality of this mechanical thermostat which, according to Mazda, has some type of defect.
Although I've examined the original control valve, I haven't seen the new replacement part, and don't know exactly what they did to correct the slow-heat issue which is causing the P0126 to be set. So the standard repair is to simply replace the complete coolant valve with the new part, as stated in the TSB.

Now on another forum, I've participated in a really long thread, where lots of information was exchanged about this same issue. And one of the most interesting things came from a guy in Europe who claims to have successfully modified the mechanical thermostat, and resolved the slow warmup problem. So naturally I have to add a disclaimer that I've never actually tried this myself, and cannot confirm that it actually does work as he said it did. However, this is IMO a zero risk thing to try, simply because a replacement coolant valve would also contain a new mechanical thermostat, so the fall back if this doesn't work is going to be to replace it anyway. I can say for certain that I'll try this mod myself, if this P0126 ever shows up in either of our vehicles.

So having explained what the deal with this is, if you want to give it a go, you'll need to remove the mechanical thermostat from the coolant control valve and test it to see at what temperature it's opening. The guy who did this said that his thermostat was opening at 60-70C, instead of the specified 105C. So if the thermostat on this vehicle is also opening way too soon, then it would be a candidate for the same physical mod that he did - very simple and easy BTW.

To get access to the thermostat, all you need to do is undo the 4 Torx bolts on the part of the valve that's closest to the front of the vehicle. Although I don't think much coolant will spill out with the system pressure relieved, you might want to drain a bit of coolant out of the rad, just in case. Once you have that front cap+hose detached from the coolant valve, you'll see the thermostat in the housing, as shown in the first picture below, from the one I disassembled previously. Then all you have to do is simply pull it out of the valve, and separate if from the plastic housing that you can see in the second picture below.

Once it's out and separated from the plastic housing, just give it the standard hot water test, and find out at what temperature it's opening. Post back if it's opening early, and you want to try the modification.

And also an FYI that I've tried a number of different ways to contact KIRPART, who is the manufacturer of the mechanical thermostat. They've never responded to any of my inquiries, and apparently could care less if anyone is having problems with one of their products.

View attachment 317824

View attachment 317825
 
Edmaz- thank you so much. I will give this a shot- I have the torx bits--- you are the example why forums like this thrive== I'm guessing with you using Celsius you aren't in the US? doesn't matter- you are appreciated where ever you are!!

I will get back with you soon- as I travel with my (pay the bills) job- and will give it a shot this weekend--

Thanks again sir much appreciated!
 
... I'm guessing with you using Celsius you aren't in the US? ...
I live in the USA, but just chose to retain everything the way Majkl wrote it up, instead of using F temps. And the thermostat also has 105C stamped on it as well, which you will see when you remove it.

AFA my part in this, I'm just the messenger. IMO the much greater value comes when someone like you is willing to actually do the grunt work, find out what happens, and report back here. I've spent lots of time with many people on all sorts of DIY efforts, and will say for certain that VERY few individuals will actually roll up their sleeves and try to follow suggestions from these forums, and also post back their results for all to see. So hats off to you for being one of them (y)
 
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