2015 Overheating?

Hello, new potential Fiesta owner here. I test drove a 2019 in a spirited manner up a local hill and power was cut within 10 mins, and restored once the car was babied for a while. Searching I became acquainted with the known overheating issue in the STs.

I've done quite a bit of searching and founds tidbits here and there, but nothing conclusive. I am looking at buying a 2015 ST. It's on the NHTSA website as having the overheating issue, but a call to Ford cold not confirm recall status or repair status. Does the overflow tank/sensor really fix the issue, or just notify the driver the coolant is low?

I've also read about the mountune 3-pass radiator as a possible fix. Can folks confirm this is a bulletproof fix, or just makes the problem less intrusive? This isn't a great solution for me as it will change the autocross class, but I could live with it.

For the last US gen ST, are all years equally affected or did Ford address the issue at some point?

Appreciate any replies, and I've enjoyed reading about the STs on the forum.

Overheating is a contentious issue. There are some who are convinced that all Fiesta STs overheat and the only solution is a bigger radiator. You'll see that on this forum. And there are others who have never experienced the problem. You'll see that on this forum as well.

I've never experienced any problem with overheating, but based on what I have read on this forum and my experience with other drivers at the ST Octane Academy, as well as the few other STs I see around town, I have some speculation.

First, there was an overheat issue with the early Fiestas, which was covered in the recall. A 2019 Fiesta ST would not be affected by that issue.

Second, a lot of the people who are experiencing overheating and have become advocates of the larger radiator also have accessports and are running tunes. They may also have modified other things in the engine. If you are making the engine make more power, it might be necessary to install a larger radiator to handle the excess heat being produced by your tune.

Third, I suspect a lot of whether a person experiences overheating all the time or not depends on how you drive. What I saw at Octane Academy, and have also seen around town, is that many drivers run in low gears and rap the engine out to redline all the time. Even when running in the autocross as well as on the track, I tended to be at least one gear higher if not two. Yet I was one of the top three times in the autocross and was consistently one of the faster ones on the track. The Fiesta ST has so much torque that it doesn't need to be whipped that hard to keep it going fast, and it actually handles better if you don't keep it spinning so hard all the time.

As far as autocross goes, people have used the Fiesta ST successfully at the national level in autocross and apparently it works well enough for them.

But those are just my opinions and observations. You'll probably hear a lot more people shouting that the cooling sucks and you have to immediately put a different radiator in as soon as you buy one.

Steve, I appreciate your input. I can certainly say the 2019 I drove did cut power and as far as I know was a factory tune, but I was flogging it repeatedly to redline. In fact I was puzzled why the car wouldn't accelerate and later learned of the issue. Having recently studied the stock torque/power curves, I'm not sure that driving style is what's best with this car. Also have ridden in a local stock ST autocross car and a remedy (common from what I understand) is to turn cabin heat on full, not something I want to do. I'm okay with a different radiator if that solves the cooling issues. I'm trying to understand is the radiator remedy valid on a 2015 with factory tune?

For reference, my experience is many year of stock Miata autocross/track and recent C7 Corvette Z06 torque monster. I'm looking for sustained fun, without imposing limp modes.

My FiST was overheating 2 months ago and it was the expansion tank. I replaced it and also put in a Mishimoto radiator and boom, problem fixed! I've been pushing it in Arizona 110 degree weather with the AC on and the needle doesn't move one bit. The only time it ever overheated before that was on a canyon run. I could almost call it bulletproof now. The mishimoto radiator has a special seal that butts up against the radiator so it pulls air very well on half of the radiator so even if the car isnt moving it still cools very well. It was about 900 after it was all said and done and def worth considering the upgrade.

The recall on 2014 and early 2015 cars was to replace a faulty coolant level sensor and the associated pieces.

Engine and engine cooling: Engine


Recall date
2017-03-26

Recall no.
17V209000

Ford Motor Company (Ford) is recalling certain 2014 Escape, 2014-2015 Fiesta ST, 2013-2014 Fusion and 2013-2015 Transit Connect vehicles equipped with 1.6L GTDI engines. If the vehicle is started and driven with an insufficient level of coolant within the engine cooling system, the engine cylinder head may overheat, crack and leak oil
Recall consequence
If the cylinder head cracks and leaks oil, the oil may contact a hot engine or exhaust component, increasing the risk of a fire.
Recall action
Ford will notify owners, and dealers will install a coolant level sensor and the supporting hardware and software, free of charge. Interim notices informing owners of the safety risk were mailed April 21, 2017. The recall began on January 5, 2018. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 17S09.


If you have a 2014 or 2015 car, replacement radiators are the same as later cars and the effect is the same. If you are trying to autocross in a stock class that doesn't allow changing the radiator, I think if you drive with the mindset that this engine is designed to exploit its torque, rather than top end power (like the old Miata), then I believe you will have a better time. As I mentioned before, the chassis is more settled when you are in the midrange, and you'll have less trouble with wheelspin and torque steer as well.