Honda Civic CRX Del Sol Fast Idle Thermo Valve

Honda P28-A50 Fast Idle Thermo Valve
Honda P28-A50 Fast Idle Thermo Valve
Item# 16500-P28-A50

Product Description

This is a sale for a brand new genuine Honda Civic CRX Del Sol Fast Idle Thermo Valve from Honda Motors, Japan. This fast idle thermo valve format is usually found on 92-95 JDM Honda Civic SiR B16A DOHC VTEC and Honda Civic EX Si D16Z6 Auto Transmission. It may also fit other applications. Buyers, please email us and make your own checks if uncertain regarding your application. This fast idle valve is usually fitted horizontally and bolted below the throttle body.

To prevent erratic running when the engine is warming up, it is necessary to raise the idle speed. The fast idle air bypass valve is controlled by a thermowax plunger. When the engine is cold, the engine coolant surrounding the thermowax contracts the plunger, allowing additional air to be bypassed into the intake manifold so that the engine idles faster. When the engine reaches operating temperature, the valve closes, reducing the amount of air bypassing into the manifold.

As the Fast Idle Valve is factory adjusted, it can be installed or removed but not recommended to be disassembled.

The Fast Idle Valve is a component whereby when faulty can cause some starting and idle-linked problems. The problem is symptomatic and will not trigger the Check Engine light. The list goes:

  1. Difficult to start engine when cold
  2. When cold fast idle out of spec (1,000 - 2,000 rpm)
  3. When warm RPM too high


In many cases, you can test whether your Fast Idle Valve is working by putting your finger at the lower port of the throttle bore, located at 8 o'clock with the throttle body upright. When the engine is cold, you should feel suction and when warmed up (cooling fan comes on), there should be no suction.

Note: Lower cost FedEx Envelope (up to 0.5-kg) shipping option available, please email us for shipping quotes.

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