Security & Fire Protection Systems/Protection One Model K3743


QUESTION: I have the Protection One model K3743. Also, the other side of the keypad read "M6829".  I have an error flashing on my keypad that reads "d0". I replaced the main battery in the alarm box in my closet hoping that would fix the problem but it didn't. The error message "d0" continues to flash and I don't know how to fix it. Can you please help with this matter? Thank you so much.


ANSWER: Hello Dodd, and thanks for your question.

Your panel is likely a Vista 20se, which means it was produced and private labeled for Protection One.

If you'd take a close look at the motherboard in the control box, see if you can find a model number there or any other identifying marks.

In the meantime, code d0 means "dialer off," and this is indicative of the alarm vendor dialing into your panel and disabling the dialer.

Have you recently terminated service or a monitoring contract?

Let me know!

best Regards,


---------- FOLLOW-UP ----------


Thank you for answering my question quickly. We just terminated our contract about 4 months ago. Is that why "d0" keeps flashing? Any other information about this model? Thank you so much for your help.


Hello again, Dodd.

Yes, since you terminated your monitoring contract, the alarm company has remotely disabled the digital dialer in your control. Not every company does this, but for the ones that do, there are two reasons.

First, disabling the dialer prevents any signals from being sent to their monitoring center.

Second, disabling the dialer prevents a competing company from coming in, taking you over as their customer, and re-using the previously installed equipment.

You have no good options; you can ignore the d0 trouble, you can renew your monitoring contract (at which point they'll turn the dialer back on), or you can have a new control and keypads(s) installed. In all likelihood, all the protective devices and system wiring can be reused with a new control.

I hope that helps, and feel free to write again if you have additional questions.

Best Regards,


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Dave Neuweiler


The design and application of burglary and fire systems for homes and businesses. Helping alarm owners understand how their system works. Helping to troubleshoot false alarm problems. Questions about monitoring issues.


Over a quarter century in the industry. Experience in installation, service, and monitoring centers. Training manager for a national protective services company; director of education and training for a national trade organization for for alarm dealers.


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