Statistics New Zealand's consumer prices manager Matt Haigh said petrol prices in the September 2016 quarter were 11 per cent lower than a year ago. Petrol makes up around 5 per cent of the CPI basket.
The Reserve Bank has a mandate to keep inflation between 1 and 3 per cent, a band it has not been in for two years now.
"Tradable inflation was stronger than expected over the quarter, despite falling petrol prices and the recent strength in the NEw Zealand dollar," ASB economist Nick Tuffley said. "The RBNZ will also take comfort from the fact that both key measures of core inflation were steady over the quarter even as headline annual inflation fell slightly."
He said he still expected the RBNZ to cut the OCR in November.
"There remains the risk of a further cut in 2017, but this CPI outcome does not add to the case for such a move."
The CPI is a basket of goods and services which includes construction and new housing costs but does not include the bulk of the housing market.