P1118 TOYOTA PRIUS Possible Causes
- Coolant heat storage tank
- Faulty engine coolant temperature (ECT) sensor for CHS (coolant heat storage)
- Low engine coolant level
- Engine coolant temperature (ECT) sensor for HST circuit open or shorted
- Engine coolant temperature (ECT) sensor for HST circuit poor electrical connection
- Faulty engine coolant thermostat
How to Fix P1118 TOYOTA PRIUS Code?
Start by checking the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Check engine light on (or service engine soon warning light)
P1118 TOYOTA PRIUS Meaning
This system uses an electric pump to supply hot coolant stored in the coolant heat storage tank to the engine cylinder head, to optimize engine start-up combustion and reduce the amount of unburned gas discharged during engine starting. Before engine starting, the ECM operates the electric water pump to direct hot coolant from the heat storage tank into the engine, to heat the cylinder head (this process is called “preheat mode”). The electric water pump operation time varies depending on the cylinder head temperature. During normal engine operation, the water valve opens the passage between the cylinder head and the heater and closes the passage between the cylinder head and the tank.
During preheat mode when the cylinder head is being heated, the water valve opens the passage between the tank and the cylinder head, to allow coolant to flow from the tank to the cylinder head. At this point, to quickly warm the intake port before engine starting, the coolant flows in the reverse direction