Misfire on cylinder 4; error code P0304 nissan altima mis... (2025)

FAQs

How do you fix a cylinder misfire P0304? ›

You should start by checking the spark plugs and replacing any that need it. If you are overdue to replace your spark plugs, you may want to replace them just to be safe. If that does not fix the problem, you should also check the ignition coil, spark plug wires, and spark plug boot.

Considering the majority of reported P0304 error codes have been fixed by spark plug or coil replacement, the expected cost to resolve the issue should come in at around $100 - $300.

Cars do not fix themselves. Misfires can damage catalytic converters and cause heat damage to valves and pistons. You'll have loss of power and horrible fuel economy. Leave it unrepaired for too long and it can destroy the engine.

The P0304 code stands for “Cylinder 4 Misfire Detected”, which means your vehicle's cylinder 4 has misfired enough times for your powertrain control module (PCM) to notice. A worn spark plug, a faulty fuel injector, and a leaking valve are some possible causes of the P0304 code.

If left untreated, a cylinder misfire can lead to significant engine damage. Worse, if you experience a bad misfire while driving, it could result in an accident. This is why it's important to treat engine misfires as soon as you detect them.

An engine misfire happens when the cylinders in the engine don't burn right or the combustion within the chamber is incomplete (or nonexistent!). Typically, engine misfires can be caused by a variety of factors, including malfunctioning coils, worn or faulty spark plugs, a leak or a faulty ignition switch.

Engine misfires are caused by many things, including: Dirty, broken or worn-out spark plugs. Low oil pressure (injector clogging) and/or overheating issues.

Worn or fouled spark plugs are one of the most common causes of engine misfires. These small but crucial components deliver the spark that ignites the fuel in your engine. If they're not working properly, your engine won't be firing on all cylinders.

In most automobiles, you could theoretically travel thousands of miles with a misfiring cylinder. The engine's other cylinders will continue to produce power. So, even if you shake and stall along the wall (and don't acquire much speed or acceleration), the car will still operate.

A misfire on its own does not usually signal a serious mechanical problem. Very often, it is just a spark plug, ignition coil or a fuel injector that needs to be replaced. However, if you ignore the problem, more cylinders could start to malfunction, possibly to the point that the engine stops working entirely.

Can engine misfire go away on its own? ›

A misfire will not normally go away on its own. Instead, the damage compounds.

Usually, fixing a misfire is a pretty straightforward repair. However, there could be a deeper issue causing it, so it's always a good idea to have a professional mechanic look under your hood.

Examine the spark plugs, ignition coils and fuel injectors.

Faulty spark plugs, ignition coils and fuel injectors can cause a P0304 code. Swap each component with an individual part from another cylinder to assess the problem. If the issue transfers to the other cylinder, it means that specific component is faulty.

Diagnostic trouble code (DTC) P0302 stands for "Cylinder 2 Misfire Detected." P0304 stands for "Cylinder 4 Misfire Detected." The code is triggered when the PCM detects frequent misfires on cylinder 2. A P0302 code can be caused by a bad fuel injector or a malfunctioning injector circuit.

The majority of the time, a misfire is caused by a faulty spark plug or another problem with the spark system, but it may also be due to: A fuel delivery problem. A mechanical engine failure. Exhaust gas recirculating.

Usually, fixing a misfire is a pretty straightforward repair. However, there could be a deeper issue causing it, so it's always a good idea to have a professional mechanic look under your hood.

To find the cause of a misfire, start with checking for trouble codes in the onboard diagnostics system with a scan tool. The codes may not pinpoint a specific part, but they should identify the cylinder or cylinders that are misfiring as well as other systems that aren't functioning properly.

Looking at the car, cylinder 4 is the furthest right, towards the driver side (US), near the shifter cables, airbox, etc.