How To Fix P0308 OBD2 Codes? Cylinder 8 Misfire Detected

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The P0308 OBD-II trouble error code can be defined as Cylinder 8 Misfire Detected. The Powertrain Control Module(PCM) will light or flash the Check Engine sign when this error occurs in a vehicle. The PCM detects this error causing the misfire from the input given from the crankshaft position sensor or the camshaft position sensor.

What does it mean?

The P0308 error is stored in the trouble code memory of the Engine Control Unit(ECU) when there is a misfire detection in-cylinder no. 8. The PCM is responsible for monitoring the rotational speed of the crankshaft for each cylinder used in the engine. Thus, when there is a variation in the speed reading from the crankshaft, The PCM stores the P0308 error code in the memory of the ECU.

Related Codes:

Symptoms of P0308

P0308 OBD2 Error Codes symptons

When a P0308 error code is stored, there are usually several issues and symptoms that we can observe in the engine functionality of the vehicle. There may be a single or a combination of multiple symptoms in the engine. It is thus crucial to check for all symptoms and issues in the vehicle. Some of the most common symptoms are listed below:

  • The check engine light is on or in most cases flashing.
  • The engine is vibrating and shaking abnormally and is running roughly.
  • There might be a lack of power from the engine while driving.
  • When accelerating, the engine might suddenly jerk or hesitate to run.
  • There might also be an odor of fuel from the exhaust.

What are the causes?

A cylinder misfire in an engine can be the result of a variety of issues with the engine. In any vehicle, misfires usually occur due to a lack of combustion or an incomplete one. The reasons for this could be anywhere from a damaged ignition coil to internal engine issues. Even though cylinder misfires in an engine could have a variety of factors, some common causes could be the source of the P0308 error. These common causes are listed below:

  • The crankshaft position sensor helps the PCM detect this error, so the sensor itself could be faulty.
  • The camshaft sensor could also be damaged.
  • There might be some vacuum leaks.
  • There could be faulty or worn-out spark plugs or wirings.
  • The engine compression might be lower than required.
  • The air/fuel mixture used could be of poor quality.
  • A defective fuel injector could also be an issue.

How do you diagnose a P0308 error code?

diagnose a P0308 error

A cylinder misfire issue could result in ignition failure and an unsafe situation if left unchecked. The P0308 error normally originates due to an issue with the compression, spark, or fuel mixture issues. Driving your vehicle despite a misfire might be catastrophic and it might end up permanently damaging your engine. 

A mechanic will first use an OBD-II scanner to check for errors in the engine. Any other additional errors like the P0308 error should be resolved to make sure everything is in working condition. Then he/she might physically check for any loose or damaged wirings or connections in the engine. The condition of the spark plugs and their wirings, the coil packs, etc. will be checked.

Sometimes, random cylinder misfires may be the result of a damaged or loose connection of wirings. The fuel system itself may also be a cause, so proper inspection of the amount of fuel, fuel pressure, etc. is done. When the fuel pressure is low, the engine does not get the required amount of fuel needed and may cause a misfire. The causes of low fuel pressure may be faulty fuel injectors, fuel pumps, or regulators.

A mechanic can also perform an engine compression test to look for any other mechanical problems causing the misfire.

Common mistakes while diagnosing

There are some common misconceptions and mistakes while diagnosing the P0308 error. There might be simple issues causing the cylinder to misfire in an engine like loose connections or worn-out cables. So, rushing to replace the cylinder coil packs or the camshaft position sensor might not be the best idea.

A thorough inspection of the engine parts related to the error like the fuel system, camshaft position sensor, cylinder coils, and the connections between those parts should be done. In most cases, loose-fitting electrical connectors or disconnected vacuum hoses are the root cause that gets overlooked.

How do you fix a P0308 error?

Proper tools are required to fix the P0308 error code or the cylinder misfire condition in an engine. A properly licensed mechanic should be equipped for resolving this error with a proper toolkit. This toolkit box may contain any equipment from screwdrivers to spark plug wires. It is however better to be stocked with at least some basic equipment like plug sockets, wires, digital multimeters, ratchet, extensions, spark plugs and wirings, compression tester and fuel pressure gauge, etc.

The repair steps might vary according to the vehicle’s model, design, and year. But there are a few repairing techniques that usually work with most vehicles:

  • Fixing any damaged wirings or connections at the ignition coils
  • Replacing worn-out spark plug wires with new ones
  • Fixing any low fuel pressure or faulty fuel pumps
  • Cleaning out any clogged fuel injectors
  • Any leak in the head gasket to be fixed
  • Broken valves, pistons or piston rings to be promptly replaced with new ones

How can you avoid further errors?

To fix a P0308 error, it may cost a lot to repair engine parts and labor costs. If any issue is left unchecked and unresolved for long, it may cause permanent engine failure and thus require a huge amount of money to replace the whole engine or the vehicle itself. It is therefore essential to be updated on your vehicle’s performance issues and any malfunctioning in the engine. 

To avoid any further P0308 errors, you need to make sure that your cylinders are in perfect condition and working properly. Any check Engine sign illumination should be resolved and the parts involved should be thoroughly tested and checked to ensure the smooth running of the engine. If you want to make sure your vehicle doesn’t get these errors, make sure your vehicle gets the proper servicing and maintenance required according to manual specifications.  

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