Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2009 Lexus GS 450hFACTORY OEM SERVICE PROCEDURE
On-Vehicle Inspection
NOTE:
- Perform the MAF meter inspection according to the procedures below.
- Only replace the MAF meter when the MAF value in the DATA LIST (with the engine stopped) is not within the normal operating range or there is foreign matter on the MAF meter platinum hot wire (heater).
- INSPECT MASS AIR FLOW METER
- Read the value the using Techstream (MAF).NOTE:
- Turn off the engine.
- Perform the inspection with the vehicle indoors and on a level surface.
- Perform the inspection of the MAF meter while it is installed to the air cleaner case (installed to the vehicle).
- During the test, do not use the exhaust air duct to perform suction on the exhaust pipe.
- Turn the power switch ON (ACC).
- Turn the power switch ON (do not run the engine).
- Turn the Techstream ON.
- Select the following menu items: Powertrain / Engine / Data List / MAF.
- Wait 30 seconds, and read the values on the Techstream.
Standard condition
Less than 0.64 g/sec.
- If the result is not as specified, replace the MAF meter.
- If the result is within the specified range, inspect the cause of the extremely rich or lean air fuel ratio. Refer to DTC P2237: Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1); DTC P2238: Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 1 Sensor 1); DTC P2239: Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 1 Sensor 1); DTC P2240: Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 2 Sensor 1); DTC P2241: Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 2 Sensor 1); DTC P2242: Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 2 Sensor 1); DTC P2252: Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 1 Sensor 1); DTC P2253: Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 1 Sensor 1); DTC P2255: Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 2 Sensor 1); DTC P2256: Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 2 Sensor 1) .
- Read the value the using Techstream (MAF).
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.