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P0305 OBD-II Cylinder 5 Misfire Detected Trouble Code




The P0305 is an OBD-II diagnostic trouble code that stands for “Cylinder 5 Misfire Detected” which means that the powertrain control module (PCM) has seen cylinder 5 misfire enough times to store the misfire code for that cylinder.

In this article, I will be talking about the P0305 trouble code, its symptoms, causes, and how to fix it.

What Does The P0305 Code Mean?

P0305 OBD-II Cylinder 5 Misfire Detected Trouble Code

A P0305 trouble code means that the vehicle’s computer has detected a misfire in cylinder number 5. Since the misfire is happening in cylinder number 5, this means that the P0305 only applies to engines with 6 cylinders (V6), 8 cylinders (V8), and 12 cylinders (V12).

The P0305 trouble code is part of a series of codes that can appear when one of your engine’s cylinders has a misfire. The last digit of the code indicates the cylinder, which in this case is the fifth.

You’ll need to look at your vehicle’s maintenance manual to determine which cylinder is the fifth in your specific engine.

There are numerous reasons that an engine could be misfiring, as well as numerous ways that it could be doing it. First, the spark plug could be firing at the wrong time. If the timing is even a little bit off, problems will happen.

It’s also possible that the spark plug isn’t firing at all or that there isn’t enough fuel in the combustion chamber to ignite. While there are numerous causes, the result is the same: the cylinder isn’t working properly.

(See also: P0300 OBD-II Random/Multiple Cylinder Misfire Detected Trouble Code)

Which Models Are Affected By The P0305 Code

MakeAffected By P0305 Code

What Are The Possible Causes of the P0305 Code?

The P0305 trouble code is caused when the vehicle’s computer detects that cylinder number 5 is misfiring constantly and as a result, a check engine light is triggered and a P0305 code is stored.

Misfires can happen for several reasons, such as a problem with the ignition system, the fuel system, or the engine itself. Most of the time, this is caused by spark plug coil packs that are damaged or worn out, especially if you haven’t had your car tuned up in a while.

Possible causes of the P0305 trouble code include the following:

  • Defective or frayed spark plugs or spark plug wires.
  • Ignition problems, such as faulty or damaged ignition coils.
  • Failure of the distributor.
  • Fuel injector failure.
  • Leak in the vacuum.
  • Fuel pressure is low.
  • Faulty camshaft or crankshaft sensors.
  • Engine timing is turned off.
  • Head gasket leak.
  • Engine compression is low.
  • The fuel is of poor quality because it is old or contaminated.

What Are The Common Symptoms of The P0305 Code?

While you may not notice any of the following symptoms, this does not rule out the possibility of an underlying problem. Misfires in engines vary in how bad they are, and the worse they are, the more obvious they are.

But this does not mean that you can just ignore the code. Ignoring even minor errors can lead to major problems.

Common symptoms of the P0305 trouble code include:

  • The check engine light is illuminated or flashing.
  • The engine runs rough, hesitates, or jerks when the car speeds up.
  • Drivers may not be noticing any difficult conditions when driving.
  • In some cases, drivers may notice a drop in fuel economy, a smell of fuel coming from the exhaust, rough idling, or less power from the engine.

Is It Safe To Drive With a P0305 Code?

No, driving with a P0305 trouble code is not safe. This code means that cylinder 5 of your engine isn’t firing right, which can hurt the catalytic converter, spark plugs, and other parts if you don’t fix it. If you see this code, you should figure out what is wrong and fix it as soon as possible.

When your engine misfires, it’s a serious problem. Your engine generates a lot of power, and the combustion chamber and cylinders are responsible for all of it. A misfire occurs when one of your engine’s explosions occurs at the incorrect time.

As it deals with errant explosions, this puts a lot of strain on various components throughout your engine. When everything is working correctly, the force generated by the explosions has somewhere to go and is pushed down by the piston.

That isn’t always the case when there is a misfire, but that energy has to go somewhere. The force of the energy attempting to escape the combustion chamber can cause additional damage and necessitate costly repairs.

(See also: P0455 OBD-II Evaporative Emission System Leak Detected (Large Leak) Trouble Code)

How To Diagnose The P0305 Code

To diagnose the P0305 trouble code, you should:

  1. To figure out what’s wrong, you have to scan, code, and write down the freeze frame data.
  2. Clear the engine and ETC codes to ensure the issue is resolved.
  3. Road tests to confirm the cylinder 5 misfire.
  4. Remove the cylinder 5 ignition coil or plug wire and inspect the outside of the coil or plug boot for evidence of spark tracking. Look for oil contamination from a leaking valve cover as well.
  5. Remove and inspect the cylinder spark plug before replacing it or switching to a different cylinder to see if the misfire has spread to the other cylinder.
  6. If no ignition problems are found, you should check the cylinder compression.

Most Common Mistakes When Diagnosing The P0305 Code

The most common mistakes when diagnosing the P0305 code are:

  • Not moving the coil to a different cylinder and rescanning to see if the misfire moves to another cylinder to determine if the coil is faulty.
  • Do not switch out one part at a time with a different cylinder to figure out which one is damaged.

How Much Does It Cost To Repair P0305 Code

MakeP0305 CodeRepair Cost
ToyotaYes$25 – $300
NissanYes$25 – $300
ChevroletYes$25 – $300
BMWYes$25 – $300
AudiYes$25 – $300
BuickYes$25 – $300
MercedesYes$25 – $300
GMCYes$25 – $300
SuzukiYes$25 – $300
TataYes$25 – $300
LexusYes$25 – $300
MazdaYes$25 – $300
MitsubishiYes$25 – $300
KiaYes$25 – $300
JeepYes$25 – $300
FiatYes$25 – $300
HondaYes$25 – $300
HyundaiYes$25 – $300
OpelYes$25 – $300
FordYes$25 – $300
FiatYes$25 – $300
PeugeotYes$25 – $300

What Repairs Can Fix The P0305 Code?

Repairs that can fix the P0305 trouble code are:

  • Changing the faulty spark plug ($25 – $35)
  • Changing the faulty fuel pump ($61 – $225)
  • Replacing or repairing the damaged cylinder ($400+)
  • Replacing or repairing head gasket leaks ($300+)
  • Changing corroded or damaged spark plug wires ($45)
  • Replacement of faulty or damaged fuel injectors ($150)
  • Repair or replace the damaged coil pack wires ($45)
  • Changing the faulty EGR valve ($115)
  • Replacing a faulty O2 sensor ($99)
  • Changing out the burned valves ($150+)
  • Replacing a faulty MAF sensor ($150)
  • Repairing the leaks in the fuel rail ($300+)
  • Repairing the leaks in the vacuum ($100+)
  • Replacing a faulty crankshaft sensor ($115)
  • Replacing a faulty camshaft sensor ($115)
  • Changing out the damaged distributor cap ($55)
  • Identifying and repairing any trouble codes stored by the PCM

How To Fix The P0305 Code

Here is how to fix the P0305 trouble code:

  • Replace the faulty spark plug or all spark plugs as a set if the failure was caused by a worn-out plug.
  • Replacing the leaking valve cover gasket, followed by the replacement of the failed coil, plug wires, and plugs.

In Conclusion

The P0305 trouble code is a very common trouble code that can be caused by a variety of issues. These issues can range from a faulty spark plug or coil to a worn-out engine component. The best way to diagnose and repair this trouble code is to use a diagnostic scanner to pinpoint the exact cause of the issue.

Once the cause has been determined, the appropriate repairs can be made to ensure that the vehicle is running properly and efficiently.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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