P0363 misfire detected – fuel supply disabled
What does this mean?
This diagnostic code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles (BMW, Mini, Mazda, Ford, Hyundai, Chevrolet, etc.). Although generic, specific repair steps may vary by make/model.
When I find a stored P0363 code, I immediately know the Powertrain Control Module (PCM) has detected a misfire and disabled the fuel injector for the affected cylinder. I might also think – with relative certainty – that the vehicle in question is of European origin.
The PCM monitors variations in the Crankshaft Position Sensor (CPS) and Camshaft Position Sensor(s) (CMPS) input signals to determine if a misfire is present, and which cylinder is misfiring. Initially, when a misfire is detected, the Malfunction Indicator Lamp (MIL) may flash rapidly for a period and then stop (instead of staying on). The flashing MIL is intended to make the driver aware that current driving conditions, combined with a cylinder misfire, could damage the catalyst. Regardless of the MIL flashing, a misfire code should be stored; although it might be stored as a pending code.
In some vehicles (typically European varieties), when the PCM detects multiple ignition cycles with a misfire code, it will disable fuel delivery to the affected cylinder. This is usually accomplished by disabling the ground pulse to the fuel injector for that particular cylinder. It’s a good idea to interrupt fuel delivery to the specific cylinder because excess fuel can cause catalytic converter failure. However, for the novice technician, this can also cause confusion during testing. Learn more about the reason for this in the troubleshooting section.
When a misfire has been detected, a cylinder misfire code has been stored, and fuel delivery to the affected cylinder has been disabled, a P0363 code will be stored and an MIL may be illuminated. One or more cylinder misfire codes usually accompany this code.
Other misfire codes include P0300, P0301, P0302, P0303, P0304, etc.
Code Severity and Symptoms
A stored P0363 code is in reaction to one or more stored cylinder misfire codes which should be treated as severe in nature.
Symptoms of this code may include:
- Rough or jerky engine operation, especially under acceleration
- Decreased engine performance
- Other misfire-related codes will likely be stored
- MIL flash is a possibility
Possible causes for setting this code include:
- Faulty spark plug(s)
- Faulty ignition coil(s) or coil pack(s)
- Moisture or oil in the spark plug well(s)
- Cracked or torn spark plug wire(s) or spark plug boot(s)
- Bad fuel injector(s)
Diagnostic and Repair Procedures
A good starting point is always to check Technical Service Bulletins (TSBs) for your particular vehicle. Your problem may be a known issue with a known fix published by the manufacturer and can save you time and money when diagnosing.
A diagnostic scanner and an accurate source of vehicle information (like All Data DIY) will be necessary to diagnose a P0363 code.
Since a P0363 code is essentially a reaction to a stored cylinder misfire code, you will need to diagnose all stored cylinder misfire codes (P0301 to P0312) before attempting to diagnose this code. While there are many tools designed to test ignition coil, spark plug, and fuel injector function, the simple method of swapping components between cylinders has proven effective for me for more years than I care to admit. This isn’t always possible with fuel injectors, but it works well with ignition coils and spark plugs, which fail much more regularly than fuel injectors. For more advice on diagnosing cylinder misfire codes, see the appropriate entry in the OBD II codes.
You will always need the scanner to retrieve stored codes and freeze frame data. The scanner is also used to clear codes after writing them down for reference as the diagnostic process continues. Once you have accomplished these tasks, clear the codes and you are ready to start swapping components for testing purposes. Obviously, spark plugs will need to be replaced in sets if the vehicle in question is near the recommended replacement interval. Nevertheless, locate the faulty part before performing any maintenance. When replacing an ignition coil for a particular cylinder, replacing the spark plug is recommended (unless the spark plugs were recently replaced). This will save you time in the long run.
The issue that creates a ton of confusion is that when some technicians find there is no ground pulse to the injector for the cylinder in question, they treat it as a malfunction instead of a reaction (caused by the PCM) to a misfire. This can make you chase your tail if you are unfamiliar with the fuel disable system used in some models.
If P0363 is stored without finding cylinder misfire codes, suspect a faulty PCM or PCM programming error.
Additional Diagnostic Notes:
The P0363 code must be cleared before the ground pulse is restored to the injector for the cylinder in question
When using the swapping method to test spark plugs, be careful when removing plugs from aluminum cylinder heads. The threads (in the aluminum) are very fragile and can be damaged if not allowed to cool properly.