Hello, I have been having problems with car shuddering when the car is cold and also with picking up speed going uphill on the motorways. my car is a 1.9 tdi, 110. Today, I cleaned the Egr Valve and manifold, this has made a difference, but will see in the next few days. I then looked to see if there were any fault codes and the following were shown... p1156 p1256 p1163 intermittent p1550 intermittent p1161 Can you please help with the breakdown of what these code mean. Many thanks. Niaz.