Engineers hope the latest increased flaring at Mossmorran should be over by Thursday.
The latest flaring, which started on Saturday, was down to a broken pump.
A spokesman for ExxonMobil Chemical said maintenance teams and a specialist pump supplier are working on the problem and expected to have it fixed by today.
ExxonMobil Chemical FEP plant manager Sonia Bingham said the focus was to return the pump to service as soon as possible.
“We are doing everything we can to minimise the size of the flare and any disturbance to the local community.
“Nobody wants flaring but it is necessary when a production issue occurs as is permitted by Sepa subject to strict regulations.”
But the latest incident at Fife Ethylene Plant has drawn widespread criticism.
Cowdenbeath Labour MP Lesley Laird said: “I have spoken to ExxonMobil, Shell and Sepa and expressed my strong concerns for local communities once again experiencing another unplanned episode of flaring and noise at Mossmorran.
“While I’m reassured by Sepa’s commitment to monitor noise, nonetheless the level and frequency of these episodes cannot be allowed to go unchecked.”
ExxonMobil and fellow site operator Shell were served final warnings by the environmental watchdog Sepa earlier this year after prolonged flaring last June.
Two other incidents are still under investigation.
Mrs Laird said the time had come for answers and serious action to get to the root cause of increasing bouts of unplanned flaring.
She revealed she had a second working group due to convene in the next few weeks and hoped all parties will be in a position to update on this latest episode but, more importantly, to clarify where what stage the ongoing investigations had reached and what actions will now be taken.
“We have reached a point, I think, where community frustrations and patience have been stretched to the limit.
“We now need to find a way through this sooner rather than later,” she said.
Sepa is monitoring noise and air quality at the site.