My 1994 Explorer gives me a 335 code(EGR sensor voltage out of range), but this model does not seem to have an EGR valve. Do I still have a DPFE sensor or should I be looking for something else? It's running rough, so could this just be a sensor problem or something bigger?

 

Unless someone has done something to it, a '94 should have an EGR valve/system.

My code list indicates that a 335 can only be a KOEO code. Because KOEO codes are set with the engine off, they are almost always electrical -- in this case, a fault in the DPFE sensor circuit. As frequently as the DPFE sensors fail on these, I'd be tempted to make sure everything is plugged in, and then just replace the DPFE sensor if something wasn't unplugged.