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 Toyota Prius BaseFACTORY OEM SERVICE PROCEDURE
Typical Enabling Conditions
Potentiometer detection
TYPICAL ENABLING CONDITIONS
| The monitor will run whenever the following DTCs are not present | None |
| Coolant heat storage system malfunction | Not detected |
| Battery voltage | 10 V or more |
| Engine coolant temperature | 0°C (32°F) or more |
| Water valve operation | Commanded |
| Response time of valve movement | Time under calculation with valve position |
Tank outlet coolant temperature detection
TYPICAL ENABLING CONDITIONS
| The monitor will run whenever the following DTCs are not present | None |
| Coolant heat storage system malfunction | Not detected |
| Battery voltage | 10 V or more |
| System status | During recovering |
| CHS tank outlet temperature difference between preheating start and engine start | 20°C (36°F) or more |
| Difference between engine coolant temperature and CHS tank outlet temperature | More than 30°C (54°F) |
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.