vs
Thermostat OEM Mazda or AISIN
Hard to say if it’s directly OE to Subaru, but I use Aisin thermostats and water pumps on every Subaru engine I do, they function the exact same and are equally as reliable as the original equipment, not to mention these thermostats are $15 on amazon compared to $40 from Subaru.
Pros: equally reliable, functions same as OE
I had the same issue on my 09 Mazda 2.3L. Everything looked good on the dash, but the thermostat let too much coolant through, over cooling the engine. My CEL came on, I reset it, and it reappeared. Long drives on the freeway in cool weather was the scenario that triggered it, as the radiator is very effective at speed, and the engine isn't working hard cruising on level ground at freeway speeds. I bought the thermostat "cover" (it's the plastic assembly with the thermostat integrated in it-- PN LF70-15-170) for $57 from Amazon and installed it last November and the CEL has not reappeared.
Pros: CEL disappeared, engine cooling fixed
Part number: LF70-15-170
After doing some research I found that AISIN is likely the supplier for the Subaru OEM thermostats so I ordered them off of Amazon (sold and shipped by Amazon) and they appear to be just that. They were close to the same price and are made in Japan. AISIN THF-007/009 appear to be true OEM Subaru thermostats for FB20B
Pros: true OEM quality, made in Japan
Part number: THF-007/009
Pick up the AISIN OEM version of your thermostat. It's pretty cheap so no reason not to get the best one instead of some cheaper alternative. Also you can test the function of your thermostat before doing the change by putting it in hot water. You can check the specs of the one you use, but for the AISIN one for my 2012 civic (9th gen), the thermostat starts opening at 170 and is fully open at 190.
Pros: OEM quality, good value, accurate opening
Vehicle:
Honda Civic
I still changed my thermostat to an Aisin unit for peace of mind, so far so good.
Pros: peace of mind, good performance
Vehicle:
Lexus
Common for the thermostat and/or coolant control valve to fail on newer Mazda 3s. It's not a big deal but you might have more coolant loss and it takes longer to warm up.
Pros: not a big deal
Cons: coolant loss, longer warm
Vehicle:
Mazda 3
My 2021 Mazda3 Turbo has classic thermostat failure symptoms: \n\n- Erratic warm-up (sometimes stuck cold, sometimes near overheating). \n- Upper radiator hose stays lukewarm even after 20+ mins of driving (revved to 3K RPM to test). \n- Housing burns hot, but hose never gets scalding\u2014clear sign of a stuck thermostat.
Pros: erratic warm-up, stuck thermostat
Cons: sometimes near overheating
Vehicle:
Mazda
Part number: PX4J-15-170
That's due to their faulty thermostat for which they don't want to assume responsibility and call it what it is - a recall.
Cons: faulty thermostat
Aisin THF-003 thermostat was used (I believe this is what I'm regretting). It's like the thermostat isn't opening? Everything else seems fine - it's clearly getting hot. Little to no heat at idle. No circulation = overheating of the engine. Is the replacement thermostat stuck shut?
Cons: thermostat not opening, overheating engine, little to no heat
Vehicle:
Subaru Impreza
Part number: THF-003
Our 2022 CX-5 Premium Plus (non turbo) is going in for its 3rd thermostat replacement next week. Each time it’s been replaced at Mazda under warranty with an OEM part. Vehicle will hit 90,000 Miles this month. Does this thermostat wear seem excessive or is it normal for these? Bought brand new and it’s been the only problem, other then general maintenance
Cons: repeated failures, excessive wear
Vehicle:
Mazda
Mileage: 144841 km
Write your review
Help others - share your experience with this part.
Comparisons
Show all
Voted AGAINST engine oil RAVENOL on the rating page
The brake pads NIPPARTS got the first review!
The brake discs Hella got the first review!
The brake discs OEM Suzuki got the first review!
For tires OEM Toyota already 25 reviews.
For tires IRONMAN already 25 reviews.
For starter motor OEM Volkswagen already 25 reviews.
In the rating best ignition coil already 13 brands participate!
In the rating best fuel pump already 5 brands participate!
In the rating best turbocharger already 4 brands participate!
In the auto rating headlights for Volkswagen Golf already 5 brands participate!
In the auto rating brake pads for Mazda 5 already 10 brands participate!
In the auto rating brake pads for BMW M2 already 5 brands participate!
Voted AGAINST engine oil RED LINE on the rating page
Voted AGAINST engine oil PENNZOIL on the rating page
