Just to resurrect an old thread, many thanks for this mdj8! Had both P1135 and P1155 (hidden by the previous owner pulling the CEL bulb :megaangry: ). Ordered 2 x DOX-0243 + tool from sparkplugs.co.uk, came next day. P1155 was a doddle at the front (after soaking in penetrating oil and warming the manifold first). P1135 rear was slightly more of a challenge, as others found the hardest bit was disconnecting the lead. If it helps anyone (as I had no spare hands at the time), I snipped the wires at the sensor end, then threaded these behind the back of the engine at the top so I could press down with one hand on the clip on the right and pull the wires (with the electrical plug attached out from the left. Came out in 10 seconds flat.
Cheers