What does it mean?
OBD II fault code P0363 is a generic code that is defined as “Misfire detected – fuelling disabled”, is set when the PCM (Powertrain Control Module) detects a misfire on one or more cylinders, and disables the fuel supply to the misfiring cylinder(s) to protect the catalytic converter(s).
Note though that while this code is usually accompanied by misfire related codes that identify the misfiring cylinder(s), other codes, such as fuel pressure, ignition, or engine sensor codes that may identify the reason for the misfire might also be present.
It should be noted that code P0363 serves a dual purpose: the first being to record a misfire on one or more cylinders (albeit without identifying the misfiring cylinder(s)), and the second being to disable the fuel injectors on the misfiring cylinder(s) when the code is set in order to protect the catalytic converter(s).
Regardless of the cause of a misfire, misfires produce very small fluctuations in the rotational speed of the crankshaft, and modern engine management systems use input data from the crankshaft position sensor to detect these variations. As a practical matter though, misfires mean that the fuel in the affected cylinder(s) is not combusted, or not combusted fully, and the uncombusted fuel is expelled through the exhaust valves into the exhaust system on the affected cylinders’ exhaust stroke.
However, when the uncombusted fuel passes through the already very hot catalytic converter, the heat in the converter ignites the fuel, with the result that the catalytic converter can reach temperatures that are high enough to melt the converter in ten seconds or less unless the PCM disables the fuel supply to the misfiring cylinder(s). Worse, though, overheated catalytic converters rank among the top ten reasons why cars catch fire, and such, many cars are destroyed in this manner.
It should also be noted that while the fuel supply to misfiring cylinders will be disabled on most cars of European manufacture, this feature is less common on American-made vehicles, meaning that this code (usually announced by a flashing red warning light), should NOT be ignored, and MUST be investigated and resolved at the earliest opportunity, if not immediately. Failure to address this code on an American-made vehicle may result in a vehicle fire that could have fatal consequences.