On-Vehicle Inspection [10/2022 - ]: Procedure

WARNING: This page is about a different car, the 2025 Lexus RX 450h+, 2025 Lexus RX 350h, 2024 Lexus RX 450h+, 2024 Lexus RX 350h, and 2023 Lexus RX 350h. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT FOR COOLANT LEAK (for Engine)

WARNING:

Do not remove the reserve tank cap, radiator cap sub-assembly or radiator drain cock plug while the engine and radiator assembly are still hot. Pressurized, hot engine coolant and steam may be released and cause serious burns.

Pre-procedure1

Remove the radiator cap sub-assembly.

Fill the radiator assembly with engine coolant, and then install a radiator cap tester.

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*a	Radiator Cap Tester

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Warm up the engine.

Pump the radiator cap tester to 103 kPa (1.1 kgf/cm² , 15 psi), and then check that the pressure does not drop.
- If the pressure drops, check the hoses, radiator assembly and engine water pump assembly (water inlet housing) for leaks.
- If there are no signs of external engine coolant leaks, check the heater core, cylinder block sub-assembly and cylinder head sub-assembly.

Post-procedure1

Remove the radiator cap tester.
Install the radiator cap sub-assembly.

INSPECT ENGINE COOLANT LEVEL IN RESERVOIR TANK (for Engine)

Check that the engine coolant level is between the LOW line and FULL line when the engine is cold.

*a	FULL Line
*b	LOW Line

If the engine coolant level is low, check for leaks and add engine coolant to the FULL line.

NOTE:

Do not substitute plain water for engine coolant.

INSPECT ENGINE COOLANT QUALITY (for Engine)
WARNING:
Do not remove the reserve tank cap, radiator cap sub-assembly or radiator drain cock plug while the engine and radiator assembly are still hot. Pressurized, hot engine coolant and steam may be released and cause serious burns.

Pre-procedure1
- Remove the radiator cap sub-assembly.
- Check if there are any excessive deposits of rust or scale around the radiator cap sub-assembly and water filler hole. Also, the engine coolant should be free of oil.
  If excessively dirty, replace the engine coolant.
Post-procedure1
- Install the radiator cap sub-assembly.