1) normal driving - sel light came on P0304 and rough engine idle 2) intake manifold gasket failed - poor idle - will not pass emission test - 60K miles 3) replaced gasket after finding many other owners had same problem even after 32K miles. Nissan should fix this under an extended warranty but they refused. Here are details of the issue: There is an engineering or material defect on the ka24de engine in regards to the intake manifold gasket. From reading the posts of dozens of owners it appears it is happening to engines made in the 00-01 time frame. If this were just some random problem then you would expect to see about the same number of posts on P0304 and gasket leaks for any year car. Just about all the posts concern specifically 00-01. The first hand evidence I had is when I took off my intake manifold and checked the condition of the gasket. The side with the leak was at cylinder 4. when I took off the gasket, the material at the cylinder 4 side was what I can only describe as "baked". it was hard and brittle and would just crack or snap very easily. The closer the gasket was to the number 1 cylinder it remained more pliable. Obviously the gasket seems to hold up better closer to cylinder 1 because it is cooler there - that is where the passage for the coolant is. This problem causes a P0304 code to get thrown. That is a misfire at cylinder 4. again, if this were some random problem - couldn't we reasonably expect a normal distribution of the cylinder misfire code from P0301, 302, 303, and 304? but that is not the case. I don't think I have seen any posts on anything other than P0304. There is extra heat around cylinder 4 above what the gasket material is rated for - which is an engine design issue. 2 cars verified so far happen to be California emission vehicles it seems plausible that the extra heat is related to the emission control devices these cars have - specifically the extra cat converter.

- Stamford, CT, USA