The P0304 engine code can compromise your driving experience, so resolve the underlying cause (or causes) immediately. If your check engine light is on and the OBD-II scanner reads a P0304 code, use the guide below to address it.
What Does the P0304 Code Mean?
Diagnostic trouble code (DTC) P0304 stands for “Cylinder 4 Misfire Detected.” This certain trouble code indicates that your vehicle’s powertrain control module (PCM) has identified an engine misfire happening in cylinder 4.
A misfire is either the absence or incomplete combustion in an engine cylinder. It happens when a pressurized air-fuel mixture is ignited inside an engine, which triggers the piston to move downward. This results in the crankshaft creating the rotational force that pushes your vehicle to move.
While engine misfires are common occurrences that could happen as isolated incidents, continuing to drive while the trouble code P0304 persists can be bad news for you in the long run.
What are the Possible Causes of the P0304 Code?
There are a lot of components in your car’s engine and each one could prove to be the root cause of the trouble code. However, due to the trouble code being specific to cylinder 4, you can eliminate some areas and components that work irrespective of its functions.
Listed below are some of the possible causes of P0304:
- Fuel delivery problems (e.g., a defective injector circuit or damaged fuel injector)
- Ignition system issues (e.g., a faulty spark plug or worn coil pack)
- Engine mechanical problems (e.g., weak piston rings or sticking valve)
What are the Common Symptoms of the P0304 Code?
Listed below are the common signs that your engine is exhibiting the engine code P0304:
- Check engine light is turned on
- Difficulty in starting the engine
- Rough engine idling
- Diminished power, especially when driving uphill
- Excessive fuel consumption
- Exhaust emits a foul odor
It’s important to note that not all of these may appear simultaneously nor consecutively.
How to Diagnose the P0304 Code
Because a lot of issues can trigger the P0304 code, it can be difficult to determine its exact cause. Let a professional diagnose the problem if you’re uncertain of your automotive know-how.
However, if you’d still like to conduct the diagnosis on your own, the videos below will help you get to know the troubleshooting process:
How to Fix the P0304 Code
When it comes to OBD-II trouble codes, there is no such thing as a “magic bullet” solution. The repair process can vary depending on the root cause of the code, or even the vehicle’s make and model.
For example, some of the most common documented fixes for a P0304 code on a 2008 Ford F-150 XL 4.2L involved replacing either an ignition coil, a spark plug, or a fuel injector. Meanwhile, the most common P0304 repair for certain Dodge vehicles, such as a 2014 Dodge Durango, Limited 3.6L, involved replacing the offending cylinder.
If you’re not confident with your automotive know-how, it may be best to leave the task to an expert. However, if you are certain of your DIY skills, identify the underlying issue that triggered the P0304 code. Then, consult online auto repair resources and guides to figure out the right solution to the problem.
You can also invest in an ALLDATA single-vehicle subscription, which can help you solve other automotive issues that you may encounter in the future.
Make sure to check your owner’s manual before attempting to fix a code P0304.