The huge blast ripped through Gorse Park in Kincaidston, which is part of Ayr, in October 2021, leaving some locals fearing a plane crash or terrorist attack.
It completely destroyed one home and damaged dozens more, sparking a massive response from the emergency services.
The Health and Safety Executive (HSE) found there were "numerous localised spots of corrosion" in the service pipe leading to Number 3 Gorse Park.
But it has concluded no further action will be taken against gas distribution network operator SGN.
The HSE released three reports following Freedom of Information (FOI) requests
One reveals three holes were found in the pipe, which meant gas from one of the leaks built up in the house before the explosion.
The report author Steve Critchlow says the extent of the damage to the property meant it was not possible to identify an ignition source.
Mr Critchlow says, in his opinion, the corrosion occurred because the plastic coating of the pipe was damaged.
He adds it was possible that damage occurred when the pipe was laid - estimated to be in the early 1970s - and the trench around it filled in, but cannot speculate on who carried out the work..
The blast site remains fenced off, with three of the four worst-affected houses knocked down while one is still standing empty.
A separate factual report by HSE found the houses were built by a predecessor to South Ayrshire Council and the pipework laid by a predecessor to SGN.
The HSE, which confirmed its investigation into the Gorse Park explosion had now been concluded, said it was not realistic to expect to be able to prove beyond reasonable doubt who was responsible for causing the damage to the service pipe.
It added that it was unlikely there would be a reasonable prospect of conviction.
A spokesperson for HSE said it recognised that the incident "caused significant disruption and concern to the residents of Kincaidston".
They added: "HSE concluded that there was no evidence to indicate that, on the balance of probabilities, SGN failed to do all that it reasonably should have done to prevent the explosion.”