Some 2008-2009 Lexus vehicles equipped with the 2GR-FSE or 4GR-FSE engine may exhibit a MIL-on condition with DTCs P0128 (coolant thermostat below thermostat regulating temperature) and/or P0116 (engine coolant temperature range/performance problem).

This applies to 2008-2009 GS350, GS450H, IS250 and IS350 vehicles produced BEFORE the production change effective VINs as follows:

MODEL PLANT DRIVE PROD. CHANGE EFFECTIVE VIN

GS350 Tahara 2WD JTHBE96S*90045581

GS350 Tahara 4WD JTHCE96S*90023172

GS450h Tahara 2WD JTHBC96S*95019778

IS250 Tahara 4WD JTHCK262*95033047

IS250 Tahara 2WD JTHBK262*95099794

IS250 TMK 4WD JTHBK262*92094026

IS350 Tahara 2WD JTHBE262*95023043

IS350 TMK 2WD JTHBE262*92017385

REQUIRED TOOLS AND EQUIPMENT

TIS Techstream (software version 4.21.002 or later is required)

Super Long Life Coolant P/N 00272-SLLC2 (9.6 – 9.8 U.S. qts)

PREVIOUS P/N CURRENT P/N ITEM

16031-31020 SAME Water w/thermostat inlet sub-assembly

Using Techstream, check for any stored DTCs.

1. If DTCs P0128 and/or P0116 are present, remove and inspect the thermostat housing and thermostat. If the thermostat assembly is securely seated in the thermostat housing, this TSB does not apply. Refer to the repair manual and follow diagnostics for the DTC(s). If the thermostat is not securely seated, refer to the repair manual for the specific vehicle for removal/installation of the thermostat assembly.
2. Once the repair complete and verified, clear all DTCs.

The example on the left shows a deformed thermostat housing. Note that the thermostat is not secured to the two posts. The example on the right shows a correct assembly.