So, your Check Engine light is on, and an OBD-2 scan tool returns the code P0305. You might also have noticed a jerk when accelerating and a decrease in fuel economy. The P0305 code is the DTC (Diagnostic Trouble Code) for a cylinder misfire in the engine, specifically cylinder 5. Find out what this means and why you need expert help to immediately fix it.
What does code P0305 mean?
It is an OBD-II trouble code signifying “Cylinder 5 Misfire Detected.” It means that the powertrain control module (PCM) sensed numerous misfires in Cylinder 5 of your car’s engine.
What are the symptoms of the P0305 error?
Loss of power with unusual vibrations is one of the most common signs of an engine misfire. Your car might also shake while idling, and the engine runs rough, sometimes with a noticeable jerk when you accelerate. You might also notice a decrease in fuel economy, as the other cylinders have to compensate for the power lost due to the misfiring cylinder. Check for fuel smell from the exhaust too.
Once the Check Engine light turns on, the OBD-II code is set in the ECM memory. If the light flashes during a misfire, it could be a warning of catalyst damage. This means that the catalytic converter is exposed to contaminants covering the working surfaces, stopping it from treating the exhaust.
What causes a P0305 code?
The following are a few reasons for the P0305 engine code to appear in your car.
- Defective fuel system
- Vacuum leakage
- Internal engine damage
- Issues with compression
- A worn-out coil pack, ignition coil, or spark plug
- Fault with the ignition system
- Engine mechanical issues
How to fix the code P0305 error
You need an OBD-II code scanner to determine the P0305 error. Once detected, the next step is to diagnose the cause and what triggered the error code. There are multiple reasons for cylinder misfires. A mechanic should ideally follow this checklist:
- Scan and ensure P0305 is the only error. If other DTC codes are detected, those should be fixed first
- Document freeze frame data
- Clear other DTC codes detected and check whether any error repeats
- Verify the misfire by test-driving your car
- Remove the ignition plug wire or coils to check for spark tracking evidence
- Switch the spark plug to another cylinder to verify the misfire is due to a faulty coil or wire
- Check for a leaking valve cover, causing oil contamination
- Check for loose engine ground wires that cause random misfires
- If no ignition problems are detected, check the fuel system (fuel pressure and fuel injectors)
- Check cylinder compression; run an engine compression and leak-down test
- Check for mechanical problems like a leaking head gasket, a broken valve spring or piston ring, burned valves, or worn-out valve guides.
- Check whether the timing belt jumped a tooth or if the engine is off-time
- Look for loose electric connectors and disconnected vacuum hoses
Usually, replacing faulty or worn-out spark plugs or leaking valve gaskets fixes the P0305 code. However, the diagnosis and repair are a time and labor-intensive process. So if you do not have mechanical knowledge, it’s best not to DIY it.
How much does it cost to fix a cylinder 5 misfire?
An accurate estimate could be made only after determining what is causing the error. However, you can expect to spend around $80 – $130 to fix a code P0305 error. In severe cases, replacing fuel system parts like the pump or injectors costs as much as $1700 – $1900. Spark plug and wire replacements cost around $60 – $240, while a vacuum leak fix can be done for $100 – $200.
Can you drive with a cylinder five misfire?
The P0305 engine code indicates a severe engine problem. Do not drive when a misfire is active; it will cause further engine damage and increase repair costs, not to mention reduced fuel economy and performance. Immediately take your car to the mechanic to avoid catalytic converter damage and ignition failure.
Can an engine misfire fix itself?
No, an engine misfire cannot fix itself unless it is an external problem. If you do not find the root cause of cylinder five misfires and take shortcuts, the error will result in a heavier bill from the mechanic.
Once a P0305 code is detected for engine trouble, you ideally need a mechanic’s help to diagnose the problem. Fixing a cylinder five misfire requires at least intermediate mechanical knowledge and specialized equipment. It is not recommended for beginners; you could end up causing more damage than there is. But it does help to be aware of the problem and the ways to fix it.
Common Queries on P0305
What is the code P0305 on a Ford Cylinder 5 misfire?
It means “Cylinder 5 Misfire Detected,” indicating your car’s PCM has detected frequent misfires in your car’s engine Cylinder 5.
What does the P0305 code for Chevy mean?
Code P0305 Chevy means “Cylinder 5 Misfire Detected.” It is an engine error code that implies the PCM has sensed misfires in Cylinder 5 of your car’s engine.
What is a P0305 problem on a BMW?
BMW code P0305 means “Cylinder 5 Misfire Detected,” meaning that the PCM has sensed many misfire events on the engine’s Cylinder 5.
What is the code P0305 on a Lexus?
It implies that the PCM has sensed a misfire in your Lexus engine’s Cylinder 5. The cylinder won’t be firing accurately, causing the code to appear.
Can a vacuum leak cause a P0305 code?
Yes, a vacuum leak can lead to the P0305 engine code. A vacuum leak can affect the air-fuel mixture in the vacuum hoses or the intake manifold. If excess air enters the cylinder or there is irregular air distribution, it can lead to many misfires.
Renée Martin is a travel and car expert who focuses on road and air travel in the U.S. For the past 6 years, she’s been helping make driving and trip planning easier and budget-friendly for everyday travelers.
