My 2007 seat Leon FR TDI car was reporting the fault P0673 so in response to this I changed all 4 glow plugs and cleared the code, however I have noticed that despite the engine light not coming back on the code has still been occurring and i am unsure as to why this would be is there anything else that could be causing this. Also I have noticed the engine sometimes shakes a little harder but not consistently I've assumed this occurs because its diesel but I have no real clue so any information would be useful, thankyou.