How do you find out if the egr valve or the electronic sensor on top of the egr valve is bad 94 f-250 351 motor
Get the engine up to operating temperature and then turn it off. Remove the vacuum hose from the EGR valve and plug it, and connect a hand vacuum pump to the EGR valve. At the tail pipe, clamp on a socket or something simular that almost completely blocks the tail pipe. Start the engine and apply a vacuum to the EGR valve. If the EGR valve is good, the engine will start to stumble and/or stall when the vacuum is applied to the EGR valve.
Reading the code might just tell you that it’s the sensor. It might not too. The test mention previously is good too.