Beware all ecoboost owners!!!!!!!!

[Flexthis2011EB]

it may not still work. PCM and BCM have to be "married" unless they got the part level, strategy, and tune file all copied over from the original. 2 different approaches. if they put the new one and reprogrammed the car to it old one will not work. if they copied the files from the old one and basically cloned it to the new one. the old one should still work. 50/50. depending on what software they're using either way could be "faster"

Would it hurt anything attempting to put old pcm back in?

[nickwalter4]

Shouldn't. If anything you'll have a DTC for each module that says 'lost communication with PCM'. Just disonnect the battery before unplugging anything else

[ZSHO]

If you only have one key probably be a wise choice to purchase another,here's a link to the PAT'S system and some[codes]to look out for.  Z     https://www.motorcraftservice.com/pdf/pats_job_aid.pdf       B1213    Less than 2 (or 3 if equipped w/Valet key) keys programmed to the system.
B1232/B2103    Transceiver internal antenna damaged. Replace transceiver.
B1342    ECU is defective (EEPROM in PCM is not working — replace PCM). PATS related
when stored in PCM only.
B1600    Non-PATS Key or damaged key.
B1601    Unprogrammed encoded ignition key detected (leave ignition on for 20 seconds       
before trying a programmed key, in Anti-Scan Mode).
B1602    Partial detection of encoded ignition key.
B1681    Transceiver signal not detected.
B2141    Non-Volatile Memory (NVM) configuration failure — No PCM ID stored in PATS.
B2139/U2510    PCM ID does not match between the PCM and PATS control
(PATS/ICM/VIC/HEC/SCIL).
B2431    Key program failure (defective key or transceiver).
U1147/U1262    Communications issue, SCP (J1850), between PCM and PATS control (PATS/ICM/   
VIC/HEC/SCIL).
U1900/U0100    Communications issue, CAN (J2284), between PCM and PATS control (ICM).
U2511/B2009       
P1260    PCM disabled the vehicle because of a PATS concern. Retrieve DTCs from        
applicable PATS control function (PATS/ICM/VIC/HEC/SCIL).