If you have the sort of heroes who are likely to steal... sorry, "borrow"... vehicles in order to make quick getaways, then it's only a matter of time until one of those vehicles has some interesting flaw or malfunction which isn't evident until it becomes truly interesting.

After all, the chase scene is so much more exciting when the heroes are having to deal with no brakes, repair an oxygen leak, or bail water at the same time.

Transcript

[SFX]: WOOOOSH!! {Falcon goes into hyperspace}
C-3PO: Chewie! Look out!
{R2 is flung backwards, falls into hole on top of Chewbacca}
[SFX]: crash!!
Leia: What the hell is happening?
Chewbacca: It's all right, Nute is no more.
Chewbacca: Something was wrong with the Falcon computer ever since Thila. Rebooting didn't fix it.
Chewbacca: I realised it was some sort of virus, so I began writing countermeasures. I spent two years making it increasingly aggressive because the virus was so insidious.
Chewbacca: It eventually cleaned the ship, and I left it active in case of reinfection.
Chewbacca: When Nute revealed himself, it all clicked.
Lando: That's why you insisted on escaping in this hunk o' junk?
Chewbacca: Precisely. All other ships were vulnerable.
Chewbacca: I just had to make sure Nute plugged into the ship before killing us all. The antivirus wiped him clean.
C-3PO: So, Artoo's still alive, right? Right?
{beat}
Chewbacca: You know, I have absolutely no idea.