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P1121 Toyota Prius Code - Coolant Flow Control Valve Position Sensor Circuit Stuck

- Code Popularity: 48,874 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P1121 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 (Stuck or Clogged Cooling System)
  • 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 P1121 Toyota Prius?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

There is a Factory Service Bulletin for the 2004-2007 Toyota Prius:
2004-2007 Toyota Prius Factory Service Bulletin OBDII Code P1121

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1121 Toyota Prius code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

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

Code P1121 Toyota Prius Description

The Engine Control Module (ECM) monitors the position of the water valve based on the valve position signal that is output by the water valve position sensor (potentiometer), which is coupled coaxially to the valve. The water valve effects control in three steps as indicated above, and the ECM determines the position of the valve according to the voltage of the respective step. In order to ensure the proper monitoring of the water valve, the ECM checks for malfunctions with the combination of the output of the potentiometer and Coolant Heat Storage (CHS) tank outlet temperature sensor. If no changes occur in the valve position signal that is being inputted into the ECM or if the response signal from the water valve is very slow, despite of the ECM commanding the water valve motor to operate the ECM determines that malfunction has occurred in the water valve position sensor circuit, and sets a Diagnostic Trouble Code (DTC).
OBDII Code P1121 Toyota Prius - Coolant Flow Control Valve Position Sensor Circuit Stuck - AutoCodes.com
P1121 Toyota Prius Code - Coolant Flow Control Valve Position Sensor Circuit Stuck

Need More Information on the Code?

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Code P1121 Toyota Prius comments

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