4th gen ECG cooler replacement

Are you sure coolant is leaking into the EGR and not the exhaust gas heat exchanger (EGHE) behind the CAT? They are both emissions control devices and one has a TSB (technical service bulletin / factory defect). If it's the EGHE you could simply bypass / loop the coolant hoses around the defect, if your car isn't covered under the TSB. It's a known defect that 2016 & 2017 model years are suspectable to .

Hope this helps....

 

“ECG”, as far as I know, doesn’t exist in Toyota nomenclature. There’s:

EGR, Exhaust Gas Recirculation

EHR, Exhaust Heat Recovery (and this one “may” have been coined at PriusChat)

the first has been problematic with Gen 3 (2010~2015 model year), but rarely has the EGR system’s “cooler” (another term coined at PriusChat; Toyota calls it “Pipe”) sprung a coolant leak. It’s a component that pulls exhaust gas at the exhaust manifold, and returns it (in measured amounts) to the combustion chambers, when the car’s at normal operating temperature.

the second, as mentioned above, has been very problematic with Gen 4 (2016~2022 model year). It’s a component in the exhaust system, adjacent to the catalytic converter. Its function is to employ exhaust heat to warm the engine coolant, when the car’s warming up. Basically to accelerate that warm up.

Who gave you the quote, a dealership? Do you have anything on paper or email/text from them? That you could post?

 

I thought it was fixed with the 2020 model year, so just 2016-2019.

 

Could be. Took Toyota 3 model years to do some of their "continuous improvement", namely acknowledge the issue, and crack down on whoever's manufacturing the Exhaust Heat Recovery component.

I think it's still the case that gen 4 owners with the issue have to battle with dealership, to get the right diagnosis, and get it paid on Toyota's dime. And the replacement components are not readily unavailable. And being combined with catalytic converter, very expensive.