Why Does P0308 Ford F150 Code Arrive? – Know Everything

What is the P0308 Ford F150 code? The powertrain trouble code shown by the system shows there is an issue with cylinder 8 of the engine. The primary symptom is severe engine misfire.

Misfire means that one or more engine cylinders cannot produce enough power. Here, the P0308 code arises to show the problem with only cylinder 8. Misfire makes it harder for the motor to keep the energy at a balanced level. It decreases the fuel economy. It can cause long-term damage if not solved the problem immediately.

So, you must know all the symptoms, reasons, and solutions for this error code to keep your engine safe and make the necessary repair in time.

Let’s learn all the details on it.

P0308 Ford F150 Symptoms and Solutions

Faulty ignition partsEngine jerking and buckling
Slow acceleration
Engine misfires
Faulty fuel systemEngine stalling
Hard start
Engine stuttering
Reduction in gas mileage
Vacuum leaksAnnoying sounds from the engine
Engine misfires
Engine sputter
Faulty PCMRandom engine stalling
Engine stuttering
Engine misfires

Defect in Ignition

Ignition parts of an engine are spark plugs, ignition coils, distributors, spark plug boots, and wires. The engine misfires when the spark plugs or spark plug boots or wires are defective. Continuous misfire leads to severe damage to the entire engine.

Besides, there are other symptoms like intermittent jerking, stumbling, and buckling from the engine. The engine will be rough at idle and slow in acceleration. When a misfire occurs, the truck will vibrate even at the running time. And mostly these seem to be root cause for shoewing P0308 08 Ford F150 code.

Solution: When the problem is with the spark plugs or other ignition parts, the engine misfires, and the system does not show the signal for two to three misfires. After misfiring several times, it shows the P0308 engine code Ford f150. So, you should repair it immediately.

Check the ignition parts closely and if found faulty, replace them. Repairing spark plugs or wires, or distributors is not wise. Even after fixing, these parts can cause issues. So, you should replace them when found faulty.

Defects in Fuel System Parts

When the fault is in the fuel system, the PCR also shows the signal as P0308 code 2004 Ford F150. The fuel pressure regulator, the EGR valve, or fuel injectors can be faulty. These problems can arise when fuel injectors are bad or clogged, the engine stalls at high temperatures. The fuel filter can be blocked. Then the engine reduces the gas mileage and loses power when there is a load.

The fuel lines can be clogged, and then it leaks and loses fuel. It makes the engine stall or causes trouble in truck starting. When the fuel pump is malfunctioning, you will get a whining sound from the fuel tank. The engine will sputter and surge.

Solution: You have to check the fuel pump, lines, injectors, filters, etc. If you find them faulty, start the steps for the P0308 code fix. Long-time issues with the fuel system can damage the engine. So, you should take proper steps soon.

Vacuum leak

When there is a vacuum leak, the truck will run normally. During running, the engine idles faster than regular. Then the engine will start to sputter, hesitate, and stall. When you try to accelerate the machine, you will face problems. And these symptoms seem mainly 2004 P0308 Ford F150 code.

A vacuum leak is not so dangerous if it is small. It is much annoying because it causes sucking sounds from the engine. When the leak becomes large, the sounds will increase, like a vacuum cleaner. The engine starts to misfire.

If the vacuum hose or tube breaks down, the vacuum leak appears. With time, it can be significant and harmful. That’s why repair should be done as soon as possible.

Solution: As a temporary fix for a vacuum leak, you seal the leak using a leak sealant. This leak sealant is specially made to close the vacuum leaks in the system. Using this sealant, you can repair vacuum leaks up to 2 microliters per second.

Check the vacuum system thoroughly when you are ready to make the solution. You may find leaking gaskets or O-rings. If they are broken or leaked, you have to replace them. They are cheap, but you may need help from professionals because the fixing steps for vacuum gaskets and O-rings are challenging.

Extra care is necessary as the plastic intake manifold easily breaks, or you may harm the fittings. So, when you get the symptoms and see the P0308 Ford F150 5.4 code, take expert help and replace essentials.

Faulty PCM

PCM can be defective for the extra thermal stress of excess heat and vibration in the engine. It fails sensitive parts of the machine, and PCM breaks.

When the fault is in the Powertrain Control Module, the P0308 Ford F150 5.4 appears in most cases. The truck will face a sudden loss of gas mileage, random stalling of the engine, and failure in emission tests. The car will start roughly, and the machine will stutter and stall.

Solution: If the PCM is faulty, you have to replace the entire PCM. Otherwise, it can increase the problem, and the engine will fall.

This Video Will Help You Too!

Frequently Asked Questions (FAQs)

How do I fix code 0308?

If you get the Ford F150 P0308 code, you have to check certain parts, including the ignition parts, fuel system parts, PCM, and engine vacuum. If you find any parts faulty like fuel filters, fuel lines, ignition spark plugs, wires, distributors, PCM, and vacuum leaks, you have to replace these parts.

What does misfire on cylinder 8 mean?

When there are any issues with the ignition of fuel to cylinder 8, the engine misfires. There are many symptoms like rough idle of the machine, stalling or stuttering engine, lack in acceleration, stuttering or sputtering of the engine, reduction in mileage, engine misfires, etc. All of these start from cylinder 8 of the engine.

What causes a misfire in cylinder 4?

The engine misfire in cylinder 4 is due to the faulty ignition system, internal engine failure, and the faulty fuel system. However, the fault in spark plugs, and coil packs can cause this problem too.


The P0308 Ford F150 code is related to cylinder 8 of the engine. When the code appears, there are several symptoms. But the main concern is the engine misfiring. It is because a long-term engine misfire can cause engine failure. Besides, this P0308 code appears when the engine has already made several misfires. So, it is essential to make the fixes immediately after getting the error code. 

Here, you will get the necessary symptoms associated with specific problems, which will let you find the issue quickly. So, make the required checks and fix them as soon as possible.

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D Conroy

Meet our senior writer and content manager of Automasterx. He has worked in several mechanical garages and mastered different vehicle diagnoses and parts repair. He never stops until finding out the ultimate solutions for any vehicle fault code. However, ensuring the only solid solutions for each vehicle malfunction is his core part of the duty, alongside analyzing fault codes and signals.

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