Viewers will see the factory worker, played by Jenny McAlpine, collapse at home after her boiler isn't fixed properly by Tyrone Dobbs (Alan Halsall).
Producers have been taking advice on the Christmas storyline from the Gas Safe Register, the Sunday Mirror reports.
"It is one of our biggest and most important storylines in a very long time and we need to make sure that it is portrayed properly as we know that scenes like this, if done properly, can save lives," a source said.
"That's why we decided to work with the Gas Safe Register. We want to make sure that we get everything accurate and right. It will have fans on the edge of their seats.
"Carbon monoxide is the silent killer and the show hopes to bring the issue to everyone."
Tyrone could face prosecution for unlawfully attempting to fix Fiz's boiler. Her daughter Hope will be staying with Chesney when the incident occurs.