Why Does General Grievous Cough in ‘Revenge of the Sith’?

However, like Anakin, Grievous made the fatal error of trusting Palpatine and Dooku. They repaid his trust by sabotaging his shuttle, which crashed and left Grievous near-death. The only way to save him? Even more cybernetic upgrades. Sound familiar?

Per the same Wookipedia report, Dooku lied to Grievous and informed him that a Jedi had been behind the sabotaged shuttle. Not only that, but Grievous’s actual organs rejected the new, cybernetic implants.