P0305 Code: Meaning, Symptoms, Causes (and How to Fix It)

The misfire is very dangerous for your vehicle engine—the engine misfires due to insufficient combustion of the air-fuel mixture. The proper combustion of the air-fuel mixture is critical for the smooth running of the engine. When any of your engine cylinders misfires, the powertrain control module (PCM) triggers a code. When your engine cylinder 5 misfires, the PCM triggers the diagnostic trouble code (DTC) P0305. This article explains the P0305 code symptoms, its causes, and how to fix it.

P0305 Code Definition

The P0305 code stands for “Cylinder 5 Misfire Detected.”

What Does the Code P0305 Mean?

The P0305 code indicates that your powertrain control module (PCM) has detected a misfire on cylinder number 5.

P0305 Code

The vehicles usually contain 4, 6, or 8 cylinders. These cylinders are arranged in different arrangements. 

To increase the engine power, you will need to increase the number of cylinders. A piston moves upward and downward inside the cylinder at a specific time.

A misfire can occur when there is not enough fuel burning within the cylinder. Having enough fuel burning is very important for the engine to work efficiently. Without it, fuel combustion will not occur, and the engine will not receive power.

When your powertrain control module (PCM) detects a misfire on engine cylinder number 5, it triggers the trouble code P0305.

The P0305 code is a part of a series of misfire trouble codes that range from P0300 to P0012. Each code between P0301 and P0312 specifies a misfire on a certain cylinder. For example, code P0302 indicates a misfire on cylinder number 2, and code P0308 indicates a misfire on cylinder number 8.

Causes of P0305 Code

  • Damaged wiring of the cylinder number 5 spark plug
  • The spark plug or ignition coil is not firing
  • Insufficient or contaminated fuel
  • Burned or bad engine valves
  • Ignition spark leaking from spark plug wire or plug boot 
  • Clogged or bad EGR valve
  • The bad spark plug in cylinder 5
  • Faulty or damaged fuel injector
  • Bad fuel pump
  • Damaged distributor cap
  • Poor compression in cylinder 5
  • Faulty O2 sensor
  • Head gasket leaks
  • Faulty MAF sensor
  • Bad catalytic converter
  • Faulty fuel pressure sensor
  • Faulty oil distributor
  • A damaged lifter or worn camshaft lobe 
  • Faulty crankshaft sensor
  • A faulty throttle position sensor
  • Vacuum leaks
  • Low fuel pressure
  • Bad camshaft sensor
  • Bad ignition coils in cylinder 5
  • Bad PCM

Symptoms of P0305 Code

  • Engine stalling
  • Fuel smell from the exhaust pipe
  • The vehicle will not start or is difficult to start
  • Poor fuel economy
  • Rough idle
  • Illuminated check engine light
  • Limp mode
  • Misfires
  • A reduction in the engine power
  • Poor car acceleration
  • Jerking when driving

How to Diagnose the P0305 Trouble Code?

  • Use an OBD-II scanner to find the trouble codes. Utilize the freeze frame data to check what’s going on. Continue the troubleshooting based on the other trouble codes you may find.
  • Clear the codes.
  • Test drive your car. If the codes return, then check other parts.
  • Inspect the coil pack, wires, or spark plug on cylinder 5 to see if it is damaged or worn. Replace any of these parts if needed. You can try to move over the spark plug and ignition coil to another cylinder to see if you get a trouble code on the other cylinder instead – if so, replace the faulty spark plugs and ignition coil.
  • Inspect the ignition coil for cylinder number 5.
  • Inspect the intake system for vacuum leaks.
  • Check the fuel injectors. If any of your fuel injectors are damaged, replace them.
  • If your car has a distributor cap and ignition cables, inspect them and replace them if needed.
  • Perform a compression test of cylinder 5 to check its compression system. 
  • Properly inspect the camshaft timing.
  • Check the shaft or timing belt if needed.
  • If all the above parts are working efficiently, and you are still getting the P0305 code, your PCM may be bad.

Common P0305 Code Diagnosis Mistakes

  • Not switching the coils and spark plug to a different cylinder and rescanning to check if the misfire moves to another cylinder to see if the coil or spark plug is bad.
  • Replacing the unnecessary components
  • Not switching one part at a time with various cylinders to detach the bad part.
  • Not clearing the PCM codes after fixing the codes
  • Not properly inspecting all the parts

Repair Cost of P0305 Code

The repair cost of the P0305 code varies according to your vehicle model, labor cost, and the repair of the relevant part. To fix the P0305, your vehicle may need one or more below given repairs:

Leaking valve fix$400 to $2,600
Spark Plug replacement$60 to $260
Fuel pump replacement$250 to $1,090
Piston ring replacement$900 to $5,100
Fuel injector replacement$1400 to $2000
Spark plug wiring repair$170 to $250
Ignition Coils$220 to $650

FAQ Section

What repairs can fix the P0305 Code?

  • Replacing the bad spark plug
  • Replacing the bad fuel pump
  • Replacing or repairing the damaged cylinder
  • Replacing or fixing the head gasket leaks
  • Replacing the damaged or corroded spark plug wires
  • Replacing the bad or damaged fuel injectors
  • Replacing or repairing the damaged coil pack wires
  • Replacing the bad EGR valve
  • Replacing the bad O2 sensor
  • Replacing the burned valves
  • Replacing the bad MAF sensor
  • Repairing the fuel rail leaks
  • Repairing the vacuum leaks
  • Replacing the bad crankshaft sensor
  • Replacing the bad camshaft sensor
  • Replacing the damaged distributor cap
  • Diagnosing and repairing any related trouble codes stored by the PCM

How Serious is the P0305 Code?

The trouble code P0305 is considered a serious trouble code. Driving with an engine misfire is very hazardous, especially if your vehicle starts to stall in the middle of the road. If your engine starts stalling, it might be hard to get it started back up, leaving you in a dangerous condition.

Therefore, you must fix the P0305 trouble code immediately. The engine misfire may also badly damage the parts of the engine, which may lead your vehicle to an expensive repair.

What would cause a P0305 code?

Engine code P0305 could be caused by a number of things, including a bad spark plug, bad fuel injector, insufficient fuel, bad fuel pump, insufficient fuel pressure, vacuum leaks, bad engine valves, or bad PCM.

Can I drive with a cylinder 5 misfire?

No, you shouldn’t drive with an engine misfire. Driving with a misfire is very dangerous and can damage your engine.

Read More
  1. P0301 Code Symptoms and Causes
  2. P0302 Code Symptoms and Causes
  3. P0303 Code Symptoms and Causes
  4. P0304 Code Symptoms and Causes

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