Engine-Codes - Toyota - P1123 2004 Toyota Prius

P1123 2004 Toyota Prius Code - Coolant Flow Control Valve Position Sensor Circuit High

- Code Popularity: 4,843 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P1123 2004 Toyota Prius?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Coolant Flow Control Valve
  • Faulty Coolant Flow Control Valve Position Sensor
  • Coolant Flow Control Valve Position Sensor harness is open or shorted
  • Coolant Flow Control Valve Position Sensor circuit poor electrical connection
  • Faulty Engine Control Module (ECM)
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How to Fix the DTC P1123 2004 Toyota Prius?

Check 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.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P1123 2004 Toyota Prius code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the P1123 2004 Toyota Prius Code Mean?

This system uses an electric pump to supply hot coolant stored in the heat storage tank into the cylinder head of the engine, in order to optimize engine starting combustion and reduce the amount of unburned gas that is discharged while the engine is started. Before the engine starts, the Engine Control Module (ECM) operates the electric water pump to direct the hot coolant in the heat storage tank into the engine, in order to heat the cylinder head (this process is called preheat mode). The duration of the operation of the electric water pump is variable, depending on the temperature of the cylinder head. During the normal operation of the engine, 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 in which the cylinder head is heated, the water valve opens the passage between the tank and the cylinder head, in order to allow the coolant to flow from the tank to the cylinder head. At this time, in order to warm up the intake port quickly before the engine is started, the coolant flows in the reverse direction.
The water valve for the Coolant Heat Storage (CHS) system, which is located at the heater hoses, controls the coolant passages to the engine, heater core, and the CHS tank in accordance with the operating conditions of the system.
The water valve consists of a water valve, valve position sensor, and valve control motor. The potentiometer, which is coupled coaxially to the water valve, converts the valve position into voltage and transmits it to the ECM in the form of a position signal.

P1123 2004 Toyota Prius Code - Coolant Flow Control Valve Position Sensor Circuit High

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