Focus throttle pedal

[Linesro21]

Hi, I had a issue with my 2010 petrol focus going in to limp mode & displaying 'engine malfunction' on dash, I took it to have a diagnostic on & it said the issue was the throttle pedal/switch sensor. We was informed by fords that the part code for my car was '4m51-9f836-bh' do I brought a 2nd hand pedal (with warranty), when my dad took my pedal off my car the 2 end numbers where different 'bk' so we rang ford's & they said both pedals will fit my car.
So new pedal on I was driving to work when the same 'engine malfunction ' warning flashed up & the car started to pull back & lose power.
I had diagnostic put on again & this time it showed the throttle pedal sensor fault again but also a wiring fault.
My question is:
Can the numbers at the end of the code make a difference? It seems a bit odd that when the old pedal was on their was only 1 problem then when other pedal was put on theirs 2 problems.
Thanks

[GreenV8S]

If Ford say they're interchangeable then they're interchangeable. Perhaps the original problem was not in the pedal sensor but in the circuit to the ECU, or the ECU itself. Do you know what sort of sensor it is? If it's an analog sensor or simple switch, you could probably test it off the vehicle.

[Linesro21]

Throttle pedal position sensor /switch 'E' circuit
That's what showed up when recovery did diagnostic. I took it to ford's garage for diagnostic after & they said that it was throttle pedal sensor, then when I took it back as same fault was happening with different pedal they put diagnostic on again & said it was still throttle pedal sensor but also a wiring fault was showing.
They can't get it in till mid April so just thout I'd check if part codes did make a difference. Don't want to spend £200 on a new pedal if it's not going to make a difference.
Thanks