Fix P0314: Mechanic’s solutions that WORKED

Learn how to fix P0314 following this simple guide. This code is one of several misfire codes, pointing out the misfire but not the exact misfiring cylinder. It is not that common code. but this guide will show you how to deal with both, the code and misfire in general.

I also made a little study of several vehicles with this trouble code + reported a fix. You can read it later in the article but first, understand what is this OBD code telling you.

P0314 quick overview

Meaning	P0314: Single Cylinder Misfire (Cylinder Not Specified)
Is it serious?	Yes, this code is serious as it indicates a misfire in one or more cylinders, which can lead to engine damage or catalytic converter failure if not promptly addressed.
Possible causes	-Worn or faulty spark plugs -Faulty ignition coils -Vacuum leaks -Clogged or leaking fuel injectors -Internal engine damage (e.g., valves, camshaft) -Faulty sensors (e.g., crankshaft position sensor) -Wiring issues or electrical faults
How to diagnose?	Perform a Swap Test: Swap spark plugs, ignition coils, or fuel injectors between cylinders to see if the misfire follows a specific component. Check for Vacuum Leaks: Perform a smoke test on the intake system to identify any vacuum leaks, which are a common cause of misfires. Inspect Ignition Components: Check the spark plugs and ignition coils for wear or damage and replace them if necessary. Test Fuel System: Ensure the fuel injectors are functioning properly by performing a pressure test or swapping injectors between cylinders. Perform Compression Test: If no other issues are found, perform a compression test to check for internal engine damage, such as faulty valves or camshaft wear.

P0314 case study: these fixes worked!

I know that every car is different and you need to do a diagnostic process for every vehicle individually, but having the real cases help you get the picture of how this code is solved and what you might have overlooked. Here are several cases from real mechanics.

How to fix P0314 on Ford

Car: 1995 Ford E-350 Econoline 5.8L
Problem: The vehicle experiences constant stalling issues, particularly under load in Reverse or Drive, despite the absence of stalling in Park or Neutral. Ignition and sensor components have been investigated and replaced, including the distributor’s hall effect sensor and the computer, yet the problem persists, with sequential port injectors failing to pulse, eliminating wiring harness issues.

Fix: The fix was done by repairing the VSS – vehicle speed sensor which seemed to shut off the fuel injectors due to incorrect speed information.

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How to fix P0314 on Volvo

Car: 1996 Volvo 960 2.9L
Problem: Single cylinder misfire P0314

Fix: The technician was able to find a vacuum leak at the intake gaskets. Fixing the gaskets repaired the misfire.

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How to fix P0314 on BMW

Car: 2005 BMW 545i 4.4L
Problem: Misfire, P0314

Fix: The car didn’t display any codes for specific cylinder misfires, but the technician did a test by unplugging fuel injectors one by one with the vehicle running. Then he found one that didn’t change the idle of the vehicle, locating the misfiring cylinder. He moved the ignition coil and spark plug to another cylinder and diagnosed a bad ignition coil. Once changed, the vehicle is running fine on all cylinders.

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How to fix P0314 on Chevy

Car: 2008 Chevrolet Suburban 2500 LT 6.0L
Problem: Misfire, P0314

Fix: The technician started by doing a smoke test to detect vacuum leaks but didn’t find anything wrong. Even the fuel pressure test or swapping the ignition coils/plugs and fuel injectors didn’t seem to make any difference. The fault was in internal engine damage, valves and camshaft replacement fixed this vehicle.

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How to fix P0314 on Dodge

Car: 1995 Dodge Neon 2.0L
Problem: Misfire, P0314, Stalling

Fix: The vehicle was running way worse in the load then idle and in that case, you should always shift your attention to the fuel system. This was proved again in this case, caused by a wiring harness short to one of the fuel injectors. Repaired harness fixed it.