A slow pit stop, the result of a problematic wheel nut, was the cause of Nick Heidfeld's fire and subsequent retirement in Hungary.
The German had a rather dramatic end to a disappointing weekend when his car caught fire as he exited the pits after his second stop of the afternoon on Sunday.
And according to Alan Permane, Renault's chief race engineer, is was all because his mechanics struggled with one of his wheel nuts, resulting in the car being stationary for too long and overheating.
"In his second pit stop we had a problem with one of the wheel nuts meaning that the car was sat at high revs for a long time," Permane explained. "This meant a build-up of heat which caused a fire.
"Although it looked spectacular it was only a small part of bodywork which burnt on the left-hand sidepod."
Heidfeld, meanwhile, admits it was a scary experience as he leapt from his stricken car as flames lapped around him.
"At Barcelona I looked left (in the mirror), saw a small fire and had time to stop," said the German.
"This one, I looked straight, saw the fire and it got hot. I really felt the temperature. It was scary, much more than Barcelona.
"It's now my second consecutive weekend without finishing, so I'm very disappointed. The last couple of races have not been what I hoped for."