On-Vehicle Inspection [10/2022 - 08/2023]: 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 ENGINE COOLANT (for Engine)
HINT:

Refer to ON-VEHICLE INSPECTION [10/2022 - ]
INSPECT ENGINE OIL
HINT:

Refer to ON-VEHICLE INSPECTION [10/2022 - ]
INSPECT AUXILIARY BATTERY
HINT:

Refer to ON-VEHICLE INSPECTION [10/2022 - ]
INSPECT SPARK PLUG
HINT:

Refer to ON-VEHICLE INSPECTION [10/2022 - 08/2023]
INSPECT AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY
1. Remove the air cleaner filter element sub-assembly.
2. Visually check that the air cleaner filter element sub-assembly is not damaged or excessively oily.
  HINT:
  - If there is any dirt or clogs in the air cleaner filter element sub-assembly, clean it with compressed air.
  - If any dirt or clogs remain even after cleaning the air cleaner filter element sub-assembly with compressed air, replace it.
3. Install the air cleaner filter element sub-assembly.

INSPECT VALVE LASH ADJUSTER ASSEMBLY NOISE

Put the engine in inspection mode.

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Rev up the engine several times. Check that the engine does not emit unusual noises.
If unusual noises occur, warm up the engine and idle it for 30 minutes or more, then perform the inspection.
HINT:

If any defects or problems are found during the inspection, perform the valve lash adjuster assembly inspection.

Refer to PROCEDURE - Step 2

INSPECT IGNITION TIMING

NOTE:

Check the ignition timing with the cooling fan off.
Turn off all electrical systems and the A/C.
When checking the ignition timing, the transaxle should be in park.

Pre-procedure1

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Warm up and stop the engine.

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Monitor Ignition Timing Cylinder #1 of the Data List.

Powertrain > Engine > Data List

Tester Display
Ignition Timing Cylinder #1

Standard Ignition Timing

-2 to 14° BTDC at idle

Check that the ignition timing advances immediately when the engine speed is increased.

Monitor Ignition Timing Cylinder #1 of the Data List.

Powertrain > Engine > Active Test

Active Test Display
Activate the TC Terminal

Data List Display
Ignition Timing Cylinder #1

Standard Ignition Timing

8 to 12° BTDC at idle

Post-procedure1

None

INSPECT ENGINE IDLE SPEED

NOTE:

Check the engine idle speed with the cooling fan off.
Turn off all electrical systems and the A/C.
When checking the engine idle speed, the transaxle should be in park.

Pre-procedure1

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Warm up and stop the engine.

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Read the value displayed on the GTS.

Powertrain > Engine > Data List

Tester Display
Engine Speed

Standard Idle Speed

1050 to 1150 rpm

Post-procedure1

None

INSPECT COMPRESSION

NOTE:

Keep the spark plug holes free of foreign matter when measuring the compression pressure.

Pre-procedure1

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Warm up and stop the engine.
Check for DTCs.
Powertrain > Engine > Trouble Codes
Remove the 4 spark plugs.
NOTE:
DTCs will be stored if the inspection is performed with the ignition coil assembly connectors disconnected. Make sure that the ignition coil assembly connectors are connected during the inspection.

HINT:

Refer to REMOVAL [10/2022 - 08/2023]

Check the cylinder compression pressure.

Insert a compression gauge into the spark plug hole.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Depress and hold the brake pedal, and turn the ignition switch to ON (READY). Then check the compression pressure.

Powertrain > Hybrid Control > Active Test

Tester Display
Compression Test

Standard Compression Pressure

Item	Minimum Compression Pressure	Specified Condition	Result
Cylinder 1	700 kPa 7.1 kgf/cm² 102 psi	870 kPa 8.9 kgf/cm² 126 psi	kPa kgf/cm₂ psi
Cylinder 2	700 kPa 7.1 kgf/cm² 102 psi	870 kPa 8.9 kgf/cm² 126 psi	kPa kgf/cm₂ psi
Cylinder 3	700 kPa 7.1 kgf/cm² 102 psi	870 kPa 8.9 kgf/cm² 126 psi	kPa kgf/cm₂ psi
Cylinder 4	700 kPa 7.1 kgf/cm² 102 psi	870 kPa 8.9 kgf/cm² 126 psi	kPa kgf/cm₂ psi
Pressure Difference between Each Cylinder	-	200 kPa or less 2.0 kgf/cm² or less 29 psi or less	kPa kgf/cm₂ psi

NOTE:

Measure the compression pressure as quickly as possible.
Noise may be emitted from the hybrid vehicle transaxle assembly. However, this is not a malfunction.

If the cylinder compression pressure is low, pour a small amount of engine oil into the cylinder through the spark plug hole and inspect it again.
HINT:
- If adding engine oil increases the compression pressure, the piston rings and/or cylinder bore may be worn or damaged.
- If the compression pressure stays low, a valve may be stuck or seated improperly, or there may be leaks in the cylinder head gasket.

Post-procedure1

Install the 4 spark plugs.
HINT:

Refer to INSTALLATION [10/2022 - 08/2023]
Clear the DTCs.
Powertrain > Engine > Clear DTCs

NOTE:
After performing the inspection, clear the DTCs and confirm that DTCs are not stored again or that the normal system code is output if using a check wire.

INSPECT CO/HC

HINT:

This check determines whether or not the idle CO/HC complies with regulations.

Pre-procedure1

Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

Run the engine speed at 2500 rpm for approximately 180 seconds.
Insert a CO/HC meter testing probe at least 40 cm (1.31 ft.) into the tailpipe during idle.

Immediately check the CO/HC concentration at idle and then at an engine speed of 2500 rpm.

HINT:

When performing a 2 mode test (with the engine idling/running at 2500 rpm), the measurement procedures are determined by applicable local regulations.

If the CO/HC concentration does not comply with the regulations, perform troubleshooting in the order given below.

Check for DTCs.
Powertrain > Engine > Trouble Codes

See the following table for possible causes, then inspect the applicable parts and repair them if necessary.

CO	HC	Problem	Cause
Normal	High	Rough idle	Faulty ignition: Incorrect valve timing Fouled, shorted or improperly gapped spark plugs Incorrect valve clearance (valve lash adjuster assembly) Leaks in intake or exhaust valves Leaks in cylinders Faulty EGR
Low	High	Rough idle (Fluctuating HC reading)	Vacuum leaks: PCV hoses Intake manifold Throttle body with motor assembly Lean mixture causing misfire Faulty EGR
High	High	Rough idle (Black smoke from exhaust)	Restricted air cleaner filter element sub-assembly Plugged PCV valve Faulty SFI systems: Fuel pressure regulator assembly Engine coolant temperature sensor Mass air flow meter sub-assembly ECM Fuel injector assemblies Throttle position sensor (built into throttle body with motor assembly) Faulty EGR

Post-procedure1

None