Renault disclosed that a known issue with its Energy Recovery System on its new power unit has crept to the forefront during testing.
The manufacturer was aware of the problem before arriving in Barcelona, but pre-season testing has apparently exacerbated the issue.
Both Renault and its customer teams have suffered ERS trouble with Palmer losing all of Tuesday morning's running when engineers ordered a complete engine change.
Verstappen was halted twice by MGU-K failures on Wednesday and Palmer was again hit by a faulty ERS on Thursday.
"We have a completely new power unit for 2017 and we have been mileage-limited with an element on the ERS side this week," explained Renault engine technical director Remi Taffin.
"We saw some similar issues in development on the dyno, however testing on track has magnified this.
"Fixes are already under way and we expect to have them in place for Melbourne so we achieve the appropriate level of reliability for the start of the season, however this has impacted our running here in Barcelona."
Palmer in particular feels he has endured 'a rubbish week', with limited running hindering the team's development programmes .
"We need to get some laps under our belt for the chassis side to work on set-up," he said.
"The engine performance we're confident we can have a fix for, so it's important we know the performance [of the car] for when we do turn up the engine."
Both the Brit and team mate Nico Hulkenberg are scheduled to drive today, the very last day of pre-season testing in Barcelona.
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