Some 2016-2019 Toyota Prius and 2017-2019 Prius Prime vehicles may exhibit one or more of the following conditions due to a coolant leak at the front exhaust pipe heat exchanger:
- Low coolant level
- MIL on with DTC P148F00
- Poor heater performance
The front exhaust pipe with heat exchanger assembly has been updated. Previous part numbers 17410-37B52, 17410-37B50 and 17410-37A00 have been updated with the new part number 17410-37D40.
Inspect for signs of coolant leakage into the exhaust system from the front exhaust pipe heat exchanger. DO NOT remove the reserve tank cap and air release valve while the engine or radiator assembly is still hot.
When the engine and exhaust system are cold, and the engine is off, unbolt and disconnect the rear exhaust pipe assembly from the front exhaust pipe assembly at the mating flange. Perform a visual inspection for signs of coolant leakage. If no visible signs of leakage are found, pressurize the cooling system to 17 psi and recheck. Inserting a borescope into the front exhaust pipe may aid in detection. If leakage is found, remove and install using the new updated part number. Clear DTCs. Perform a health check to confirm if any DTCs remain. Start the engine, warm to operating temperature and test drive to confirm the repair.
