P1150 2004 TOYOTA PRIUS Possible Causes
- Coolant Heat Storage Tank Outlet Temperature Sensor
- Water Valve (Coolant Flow Control Valve)
- Cooling System (Clogging)
- Engine Control Module (ECM)
How to Fix Code P1150 2004 TOYOTA PRIUS?
Start by checking the “Possible Causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
- Check Engine Light On (or Service Engine Soon Warning Light)
P1150 2004 TOYOTA PRIUS Meaning
This system uses an electric pump to supply hot coolant stored in the Coolant Heat Storage (CHS) tank to the engine cylinder head, in order to optimize engine start-up combustion and reduce the amount of unburned gas discharged during engine start-up. Before starting the engine, the Engine Control Module (ECM) activates the electric water pump to direct hot coolant from the CHS tank into the engine, to heat the cylinder head (this process is called “pre-heat mode”). The operating time of the electric water pump 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 the pre-heat mode where the cylinder head is 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 time, in order to warm the intake port quickly before starting the engine, the coolant flows in the reverse direction.