You can test it before replacing too. You should get 10-11V on the terminals when you try to start the car. If you dont get this voltage, the problem could be with the fuel pump relay. Infact, it is not clear if the cold start valve is supposed to work in summer weather. I know mine on a 87 260E works in summer but some say that it only works in extreme cold climate.

If you get the voltage, check the resistance across the terminals of the valve, for this test disconnect the wiring. You should get a low resistance, few ohms.

If the resistance is o.k., put the wiring back on, pull the valve out and check if gas is sprayed when you try to start.

From these tests you can tell if the valve needs replacement. And yes, these valves are not cheap, if used is o.k., try ebay too.

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Saumil S. Patel