Diesel 100 once visited the Island of Sodor in 2019, and caused trouble for the steam engines while she was there. During her visit, she found Glynn, the engine responsible for keeping Sodor alive, and chased her, making her crash. Following the accident, Glynn's caretaker, Sir Topham Hatt, hid Glynn in a siding and tried to restore him, but failed to bring him back up to steam.
Several years later, Diesel 100 returned to Sodor when Dowager Hatt was on holiday, intending to destroy Glynn once and for all. She was first seen by Thomas and Gordon when she raced past them at Killaban Station, and brought her two lapdogs, Jacob and Tony, to the railway, who were present when she was scheming. She caused several problems for the steam engines, such as dumping sneezing powder around Tidmouth Sheds and later destroying the scaffolding that had been placed beside the shed.
When Mr. Percival travelled across Sodor to find the windmill, Diesel 100 found him and held him over the Big Dipper, intending to drop him. However, Mr. Percival managed to escape by cutting the hydraulics to her claw with a pair of wire cutters, causing her to fling Mr. Percival across the island and to the windmill. Diesel 100 was later present at the Coaling Plant, where she was covered in coal when she was teaching Jacob and Tony “how to stop being stupid”. After Mr. Percival Jr. flew in the air after riding the windmill's sails, he landed on Diesel 100's cab, who raced across the island and to the smelter's yard, where she tried to push Henry and Mr. Percival Jr. into the melting pit. Fortunately, Mr. Percival Jr. and Henry managed to escape by using the last of the former's gold dust.
After Glynn was brought back up into steam and returned to Sodor, Diesel 100 found him and began to chase him, Thomas, Percy, Nia and Sir Topham Hatt across the island, until they reached the viaduct, but not before Jacob and Tony betrayed her. Glynn, Sir Topham Hatt, Thomas, Percy and Nia managed to cross the viaduct safely, but Diesel 100 was too heavy for the rails and plunged into a barge of sludge below the bridge, and was sent away in disgrace.
Diesel 100 later returned to Sodor months later under unknown circumstances. It can be assumed, however, that Sir Topham Hatt decided to give her a second chance. She was seen working at the scrapyard, loading piles of scrap into trucks. The very sight of her return caused Thomas and Percy to shudder in fright.
She was sent back to the Mainland in 2021 and was destroyed in 2022.