DEALER PART BACKORDERED UNTIL JUNE 2025 AND THE HEATER HOSE PRICE IS NOW $12.13
UPDATED: 1/7/2025
The P148F-00 error code was related to the Exhaust Heat Exchanger…
To start the fix, you’ll need a Gates 18777 Premium Molded Heater Hose, they are $9 on Amazon.
From here, get under your car and locate the catalytic converter. Once you remove the two hoses, install the Gates 18777 to create the bypass, and that’s it!
This is meant to be a bandaid until we get the car to the dealership to replace the heat exchanger under warranty!
Update: the bypass was only part of the story
I still stand by this as an emergency workaround, but I want to be clear about the bigger lesson now: the Prius heat exchanger bypass is not the fix. It can stop one coolant-loss path, but it does not prove the engine is healthy after the car has been low on coolant.
That is why I now tell Gen 4 Prius and Prius Prime owners to push for engine-health testing, including a compression check when appropriate, before treating the bypass like a long-term repair. In my case, the larger heat-exchanger story eventually turned into Toyota replacing the Prius Prime engine.
