AutoCodes – Toyota – P1123 2009 Toyota Prius

P1123 2009 Toyota Prius Code - Coolant Flow Control Valve Position Sensor Circuit High

Quick Answer

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. Common causes include Coolant Flow Control Valve, Faulty Coolant Flow Control Valve Position Sensor, Coolant Flow Control Valve Position Sensor harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1123 2009 Toyota Prius indicates Coolant Flow Control Valve Position Sensor Circuit High.
Common causes: Common causes include Coolant Flow Control Valve, Faulty Coolant Flow Control Valve Position Sensor, Coolant Flow Control Valve Position Sensor harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 11,616

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 12, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1123 2009 Toyota Prius Description

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.

OBDII Code P1123 2009 Toyota Prius - Coolant Flow Control Valve Position Sensor Circuit High - AutoCodes.com — P1123 2009 Toyota Prius Code - Coolant Flow Control Valve Position Sensor Circuit High

What does this mean?

What are the Possible Causes of the DTC P1123 2009 Toyota Prius?

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)

How to Fix the DTC P1123 2009 Toyota Prius?

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1123 2009 Toyota Prius code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1123 2009 Toyota Prius code?

Need more information on how to fix the P1123 2009 Toyota Prius code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1123 2009 Toyota Prius code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1123 2009 Toyota Prius Code

1. What are the common symptoms of OBDII code P1123 in a 2009 Toyota Prius?

The common symptoms include poor engine performance, decreased fuel efficiency, and potential overheating issues.

2. What does the OBDII code P1123 indicate in a 2009 Toyota Prius?

OBDII code P1123 indicates a malfunction in the Coolant Flow Control Valve Position Sensor Circuit, specifically a high voltage condition.

3. What are the possible causes of OBDII code P1123 in a 2009 Toyota Prius?

Possible causes include a faulty coolant flow control valve, a malfunctioning position sensor, wiring issues, or a problem with the engine control module (ECM).

4. How can I diagnose OBDII code P1123 in my 2009 Toyota Prius?

Diagnosis involves checking the coolant flow control valve, inspecting the wiring for any damage, and testing the position sensor for proper operation using a multimeter.

5. Can I continue driving my 2009 Toyota Prius with OBDII code P1123?

It is not recommended to drive your vehicle with this code as it can lead to further engine damage and potential overheating issues. It is best to address the issue promptly.

6. How can I repair OBDII code P1123 in my 2009 Toyota Prius?

Repair typically involves replacing the coolant flow control valve if faulty, fixing any wiring issues, or replacing the position sensor if needed. Resetting the fault code using a diagnostic tool is also necessary.

7. Are there any DIY tips for addressing OBDII code P1123 in a 2009 Toyota Prius?

While some basic troubleshooting like checking for loose connections or damaged wires can be done, it is recommended to consult a professional mechanic for a proper diagnosis and repair.

8. Can a faulty Coolant Flow Control Valve Position Sensor impact the overall performance of my 2009 Toyota Prius?

Yes, a faulty sensor can lead to poor engine performance, decreased fuel efficiency, and potential overheating issues if not addressed promptly.

9. How long does it typically take to repair OBDII code P1123 in a 2009 Toyota Prius?

The repair time can vary depending on the exact cause of the issue and the availability of parts. It is best to consult with a mechanic for a more accurate estimate.

10. Is it necessary to clear the OBDII code P1123 after repairing the issue in a 2009 Toyota Prius?

Yes, it is essential to clear the fault code using a diagnostic tool after repairing the underlying problem to reset the Check Engine Light and ensure proper operation of the vehicle.

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