Renault boss Cyril Abiteboul says the French team is in the middle of a "multi-year" task to catch the big three teams.
The comments come after China, where despite making reliability fixes for its significantly more powerful 2019 engine after Bahrain, Nico Hulkenberg once again retired.
"Nico had a problem around the MGU-K," Abiteboul told France's Auto Hebdo.
"It is difficult because it means that we are not totally out of our reliability problems.
"It was a software problem that is related to all the changes we have made to react to the glitches of the beginning of the season," the Frenchman added.
There was some good news in China. After a difficult start to his Renault career, Daniel Ricciardo finally opened his points account with seventh place.
"It's good for the team but a frustrating race," said Abiteboul.
"It does allow us to forget Bahrain and start like in Melbourne, where Nico was seventh. But we must do better in all aspects.
"We are a little slower than we would have liked, but we have to work, not complain. It's a multi-year job to reduce and then close the gap," he insisted.
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