07 Yaris P0420

[Minimanirl]

Good morning all, first post here. 

My girlfriend has recently started driving so we picked her up a 07 yaris to learn in. It had failed it’s NCT on a few minor issues such as drop links and headlights out of focus. 

While we were out driving the other day, the engine management light came on, so I ran my diag. on it (I mostly work on minis) and it brought up the p0420 code. The cat was replaced last year, and it didn’t even come close to failing the emissions test during its NCT. She’s a very nervous driver, so wouldn’t drive it on at all, and really only does 10 or 15 minute trips. I cleared the code and gave a good drive, and it hasn’t reappeared since. 

It has its re test coming up, and I was hoping could someone tell me is this a common code to pop up in these yaris’? My Toyota knowledge stops in the mid 90’s, we have a ST185 gt4 celica in the garage as a toy so beyond that I know very little about them! 

Any input is greatly appreciated. 

Brian.