P0304 2008 Ford Fusion Code - Cylinder 4 Misfire Detected
Quick Answer
Misfire is defined as a lack of combustion in a cylinder due to the absence of a spark, incorrect fuel metering, low compression, or any other cause. Common causes include Faulty Spark Plug #4, Clogged or faulty Fuel Injector #4, Faulty Ignition Coil #4. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0304 2008 Ford Fusion indicates Cylinder 4 Misfire Detected.
- Common causes
- Common causes include Faulty Spark Plug #4, Clogged or faulty Fuel Injector #4, Faulty Ignition Coil #4.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0304 2008 Ford Fusion Description
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.
The Malfunction Indicator Lamp (MIL) blinks once per second when detecting a misfire severe enough to cause catalyst damage. If the MIL is in a steady state due to a misfire, this indicates the threshold for emissions was exceeded and caused the vehicle to fail an inspection and maintenance tailpipe test.
This Diagnostic Trouble Code (DTC) sets when the misfire detection monitor detects an engine misfire in cylinder 4.
What are the Possible Causes of the DTC P0304 2008 Ford Fusion?
- Faulty Spark Plug #4
- Clogged or faulty Fuel Injector #4
- Faulty Ignition Coil #4
- Fuel Injector #4 harness is open or shorted
- Fuel Injector #4 circuit poor electrical connection
- Ignition Coil #4 harness is open or shorted
- Ignition Coil #4 circuit poor electrical connection
- Insufficient cylinder 4 compression
- Incorrect fuel pressure
- Intake air leak
How to Fix the DTC P0304 2008 Ford Fusion?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0304 2008 Ford Fusion code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0304 2008 Ford Fusion Code
What does OBDII code P0304 mean for a 2008 Ford Fusion?
P0304 indicates that the engine control module (ECM) has detected a misfire in cylinder 4 of the engine.
What are the common symptoms of code P0304 in a 2008 Ford Fusion?
Symptoms may include a rough idle, hesitation during acceleration, reduced fuel economy, a flashing or steady check engine light, and possible engine vibration.
What causes a cylinder 4 misfire in a 2008 Ford Fusion?
Common causes include a faulty spark plug, a bad ignition coil, a clogged fuel injector, low cylinder compression, or vacuum leaks near cylinder 4.
Can a bad spark plug cause the P0304 code?
Yes, a worn or damaged spark plug in cylinder 4 is a frequent cause of this code and should be inspected or replaced.
Is it safe to drive with a P0304 code on a 2008 Ford Fusion?
Driving with a misfire can damage the catalytic converter and other engine components, so it’s best to address the issue as soon as possible.
How do I diagnose the cause of a P0304 code?
Start by inspecting the spark plug, ignition coil, and fuel injector for cylinder 4. A compression test or leak-down test may also be needed to check for internal engine issues.
What tools are needed to fix a P0304 code?
Common tools include a spark plug socket, a multimeter for testing the ignition coil, a fuel pressure gauge, and an OBDII scanner to clear the code after repairs.
Can a dirty fuel injector cause a cylinder 4 misfire?
Yes, a clogged or malfunctioning fuel injector can disrupt the fuel delivery to cylinder 4, leading to a misfire.
How much does it cost to repair a P0304 code?
Costs vary depending on the cause. Replacing a spark plug or ignition coil may cost $100-$300, while more extensive repairs, like fixing internal engine issues, could be significantly higher.
What should I do after repairing the issue causing the P0304 code?
After repairs, use an OBDII scanner to clear the code and test drive the vehicle to ensure the misfire is resolved and the code doesn’t return.
Discuss the causes and fixes for P0304 2008 Ford Fusion OBDII Code
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