2003 Nissan Murano P0300 Code: Diagnosis After Replacing Coils, Spark Plugs, and Fuel Injector
I recently worked on my 2003 Nissan Murano and replaced all the spark plugs, ignition coils, and one fuel injector. Despite these changes, I'm still receiving a P0300 random misfire detection code. When I tested by unplugging each coil individually, the engine remained unstable when the first coil was removed, but when I unplug the second coil, the car begins to stall. This suggests that at least one ignition component is not functioning properly. I'm now wondering if a faulty or incompatible coil is still causing the issue—especially since I've already replaced all components. Could there be another underlying cause? I suspect the problem might stem from incorrect parts (e.g., aftermarket coils) or an unaddressed fuel system issue.
Did you use the correct NGK spark plugs for your 2003 Nissan Murano? Ensure you're using OEM or properly matched parts—aftermarket coils are not recommended and can cause misfires. This P0300 code is typically related to a cylinder misfire, which may point to a COP (coil-on-plug) issue in a 6-cylinder system. Was the P0300 present before you replaced any components? Also, please check your fuel system pressure and leak-down test—these can contribute to misfires even with new ignition parts.