Yeah the fault and just low pressure are different. Wouldn't hurt to go ahead and check the pressure regardless.
As for diagnosing which one is damaged, I'd say go to Ford. They likely have a machine that will communicate with each sensor and find the one that isn't responding. Much like the calibration tool you can buy for aftermarket wheels.
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2011 V6 Race Red - Airaid CAI , BBK 73mm Throttle Body, 3.73 FRPP Gears, BBK Longtube Headers , BBK Off Road X-Pipe , Borla ATAKs , SR Performance Strut Tower Brace, MPT 91R Tune, Powerstop Rotors and pads, JLT Oil Seperator, Koni STR.T Struts & Shocks, Eibach Pro Line Springs, BMR Adjustable Panhard Bar, J&M Caster Camber Plates, Mickey Thompson Street Comps on 19" Laguna Seca Hyper Black Wheels, Several other aesthetic mods