P1151 2004 TOYOTA PRIUS Possible Causes
- Coolant heat storage tank
How to Fix Code P1151 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)
P1151 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 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 electric water pump’s operating 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 pre-heat 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 time, in order to warm the intake port quickly before starting the engine, the coolant flows in the reverse direction.