Joining the campaign trail in Adelaide on Wednesday, Mr Howard dismissed a new opinion poll that put Labor in a commanding position to win government in its own right.
"I've seen a lot of polls. I've been buffeted by them in the past and I've been exalted by them," he said.
"What I know is they can often be a very poor guide. Tune in on Saturday."
Mr Howard joined Premier Steven Marshall in the government's most marginal seat of Newland, one of four the Liberals hold by a margin of two per cent or less.
He said he believed voters would return the government because the premier and the Liberal government had put the state back on the map, economically.
"The truth is Steven Marshall has turned around South Australia's economy," the former PM said.
"If you look at an analysis based on reality, it is amazing the job this man has done in just four years.
"I don't want to see South Australia slip back into the slow economic lane."
In the latest Advertiser-YouGov poll Labor was clearly ahead of the Liberal government, 56 per cent to 44 per cent, on a two-party preferred basis.
That could be enough to have the opposition pick up as many as six seats, sufficient for it to govern in its own right.
The poll of 835 voters, conducted between March 7 and 13, also showed Labor extending its lead from a Newspoll in February which had the party in front by six percentage points.
And it had Labor leader Peter Malinauskas ahead of Mr Marshall as the state's preferred premier, with 45 per cent support compared with 40 per cent.
Mr Malinauskas said opinion polls counted for absolutely nothing.
He said the only thing that mattered was installing a government with a plan to fix the problems in health.
"There's only one party that's got that at this election," Mr Malinauskas said.
