Toyota prius 3rd gen EGR Valve Assembly (D10)

Toyota Prius 3 ^rd Generation (XW30)

EGR Valve Assembly Wiring Guide: DIY Pinout Diagram

What is: A vehicle EGR (Exhaust Gas Recirculation) Valve Assembly is an emissions-control component that recirculates a measured amount of exhaust gases back into the intake manifold. By lowering combustion temperatures, it reduces NOx emissions, improves fuel efficiency, and helps prevent engine knocking. The assembly includes the valve, actuator, and passages that regulate exhaust flow based on engine load and temperature for cleaner, smoother operation.

EGR Valve Assembly (25620-37120)

Toyota Prius 3rd gen EGR valve assembly close-up view (25620-37120).

EGR cooler and valve assembly layout on Toyota Prius hybrid engine.

EGR cooler and valve assembly layout on Toyota Prius hybrid engine.

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1. Introduction

      The  Toyota Prius 3rd Generation EGR Valve Assembly (25620-37120) is a key emissions-control component designed to enhance engine efficiency and reduce nitrogen oxide (NOx) emissions. It recirculates a precise amount of exhaust gas back into the intake system, lowering combustion temperature and improving overall fuel economy. This assembly works together with the EGR cooler and intake passages to ensure smooth engine performance, especially during cruising and light-load conditions. In the 1.8L 2ZR-FXE hybrid engine, the EGR valve helps maintain optimal air-fuel balance, reduces knocking tendencies, and supports cleaner combustion. Proper EGR flow is essential for preventing rough idle, reduced power, and increased emissions.

1. Related Devices & Components
   • EGR Cooler :-Cools exhaust gases before entering the intake, improving efficiency.
   • EGR Pipe / EGR Transfer Tube :- Carries exhaust gases from the exhaust manifold to the valve and cooler.
   • Intake Manifold:-Receives recirculated exhaust gases mixed with fresh air.
   • EGR Control Solenoid / Stepper Motor :- Built into the valve to regulate opening and closing.
   • EGR Temperature Sensors:-Monitor exhaust gas temperature for precise EGR flow.
   Engine & ECU Units Involved
   • Engine Control Module (ECM):-Controls EGR operation based on load, speed, and temperature.
   • Mass Air Flow (MAF) Sensor:-Helps ECM calculate airflow changes due to EGR.
   • Manifold Absolute Pressure (MAP) Sensor:-Detects pressure changes caused by EGR flow.
   • Coolant System :- Helps maintain proper temperature in the EGR cooler.

2. EGR Valve Assembly Wiring Diagram & Pinout

A. Connector Location

• EGR Valve Assembly Position: Located on the engine’s rear near the firewall, connected to the EGR cooler and intake manifold.


• Connector Type:
  • D10 (6 pin) Black housing

B. Wiring Table

EGR Valve Assembly (D10)

D10 TERMINALS OF EGR Valve Assembly CONECTOR

Terminal No	Symbol (Pin Definition)	Wiring (Color Code) & Color	Electrical Paths
D10-1	EGR4	(LG) Light Green	➔ D28 42 (EGR4) [Engine Control Module]
D10-2	+B1	(B) Black	➔ ✠ ➔ DA2 4 ➳ 1 2 ➤ 10A Blade Fuse [EFI NO.2]
D10-3	EGR2	(V) Violet	➔ D28 44 (EGR2) [Engine Control Module]
D10-4	EGR1	(R) Red	➔ D28 45 (EGR1) [Engine Control Module]
D10-5	+B2	(B) Black	➔ ✠ ➔ DA2 4 ➳ 1 2 ➤ 10A Blade Fuse [EFI NO.2]
D10-6	EGR3	(Y) Yellow	➔ D28 42 (EGR3) [Engine Control Module]

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