Diagnosis & Repair
WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
- Drain cooling system. Remove and test thermostat. Replace thermostat as necessary. If thermostat is okay, install thermostat and refill cooling system. Go to next step.
- If any other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0128 is displayed, replace ECM and retest system.