A split valve pressure test plug is provided for high pressure fluid systems to sense pressure or temperature by means of a test probe and gauge. The test probe is inserted within split valve resilient valve core members in the test plug. The split valve core members are separable and are interfitted in a male-female relationship to provide for improved sealing upon removal of the test probe. A retainer strap is further provided which retains a cap for the test plug, permits use of a wrench without interference and acts as a sealing ring in addition to a separate gasket when the cap is tightened.
