Quote from an earlier post of mine -
"Still, go on then, use a 'found' Engineer code, have a play, mess it up, see what it costs you to get it corrected.
Mess it up, have a break-in, alarm does not go off, call the alarm company and moan about their system not working, engineer attends, looks at the Log, finds the changes, date and time do not 'marry up' with an engineer on site, insurance Co asks for a copy of the Log, whoops, NO insurance payout, unauthorised tampering with the alarm.
Now do you understand Engineer Codes?
PS
& yes the above has happened many times, people never learn, they always think they know best."
I forgot, there are only a very few professional alarm engineers here who take security seriously.
Read the above, step back and really think about what I've written.
Take over an alarm and not default and re-programme, all that is, is doing it 'on the cheap' to make a quick buck.
The difference between a fake & real handbag
If you're talking about a DiY, hell, why worry, do what you like, you know what DiY stands for don't you, Destroy it Yourself.