Mercedes has revealed the "biggest surprise" which "characterised" the start of their 2023 season.
The team suffered from a power unit-related retirement for George Russell during the Australian Grand Prix, while Lance Stroll was also hit with issues during the race in Saudi Arabia forcing him to retire in the customer Aston Martin.
Mercedes was praised for its power unit reliability throughout the 2022 season, having achieved a 100 per-cent reliability record.
These early failures raised alarm bells for their engine division, Mercedes High Performance Powertrains according to Managing Director, Hywel Thomas.
"The biggest surprise and disappointment we had was the first three events. We suffered a DNF in each event across the works and customer teams," he said.
"That really forced us to focus on understanding how we got into that situation and make sure we weren't just putting sticking plasters over the issues. That characterised the first quarter of the season.
"It caused a lot of reflection and change in the way we were doing things to make sure we didn't have further repeats."
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Mercedes perfect weekend
Mercedes has not suffered a power unit failure since the changes, however this is likely to be tested in the second half of the season as drivers utilise more components from their allocation.
Thomas explains the internal processes that Mercedes changed to ensure that failures are not repeated: "Part of that reliability push has been on how we make the perfect race weekend.
"For example, the perfect Friday when we take the Power Unit out of the box.
"We've had too many issues on a Friday, so we've done an enormous amount of work to try and understand what the Power Unit is going through, to make sure we've got all our set-ups correct."