Ignition Systems ControlOBD2 Codes

P0305 – Meaning, Causes, Symptoms, & Fixes

P0305 cylinder 5 misfire detected

What Does Code P0305 Mean?

  • P0305 definition: Cylinder 5 misfire detected
  • Issue Severity: SEVERE – Stop driving immediately
  • Repair Urgency: Fix this code immediately (same-day if possible) to avoid ignition failure, catalytic converter damage, and dangerous conditions
  • Diagnosis: A misfire can be caused by anything from faulty spark plugs to low engine compression. Because there are so many variables that could cause a misfire, the best cost savings is to take your car into a shop to have it diagnosed as quickly and accurately as possible.

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Your vehicle moves when gasoline is burned and power is generated inside a chamber known as the cylinder. Most engines have a 4, 6, or 8-cylinder engine, where more cylinders typically mean more power. Power is generated by pistons that move up and down while fuel is ignited at very specific times. A misfire typically occurs when the timing of this ignition is off.  P0305 indicates that cylinder #5 is experiencing misfires. 

P0305 Causes

Misfires can be caused by many reasons from a faulty ignition system, fuel system, or internal engine failure. The most common reason for this to happen is faulty or worn-out spark plug coil packs, especially if it’s been a while since you had a tune-up.

  • Faulty or worn spark plugs and/or spark plug wires
  • Ignition issues, including failing or damaged ignition coils 
  • Distributor failure 
  • Faulty fuel injector
  • Vacuum leak
  • Low fuel pressure
  • Camshaft and/or crankshaft sensor defective
  • Engine timing off
  • Leaking head gasket
  • Low engine compression
  • Poor quality fuel that is old or contaminated

P0305 Symptoms

  • Check Engine Light is on or flashing
  • Engine runs rough, hesitates, or jerks when accelerating
  • Drivers may not notice any adverse conditions when driving
  • In some cases, drivers may experience decreased fuel economy, fuel smell from exhaust, rough idling, or lack of power from the engine
  • Commonly associated with error codes: P0300, P0301, P0302, P0303, P0304, P0306, P0307, P0308

How Do I Fix Code P0305?

With a misfire fault, the first step is to get it diagnosed to figure out what is causing the engine to misfire. 

If your vehicle is misfiring and you’re not comfortable diagnosing this issue at home, we recommend finding a RepairPal certified shop nearby to pinpoint the problem and give an accurate estimate for repairs. 

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

Right shop, right price

We've partnered with RepairPal to recommend certified and trustworthy shops in your local area. 

  • Upfront cost estimates
  • Minimum 12-month, 12,000-mile warranty
  • Fair price guarantee

How Much Does It Cost to Fix Code P0305?

P0305 can be caused by anything from old spark plugs to vacuum leaks to poor engine compression. It’s impossible to give an accurate estimate without properly diagnosing the issue first. 

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0305 code.

Possible Repair Costs for P0305

Once properly diagnosed, P0305 may require one or more of the following repairs to resolve the underlying issue. These prices are based on national averages and include parts and labor. Your cost may differ depending on your location and type of vehicle.

  • Spark plugs: $66-$250
  • Ignition Coils: $230-$640 (some cars require Intake manifold removal)
  • Spark plug wires: $180-$240
  • Fuel injectors: $1500-$1900
  • Vacuum leak: $100-$200
  • Fuel pump: $1300-$1700
  • Fuel pressure regulator: $200-$400

DIY Steps to Diagnose Code P0305

Engine code P0305 could be caused by a number of things, including faulty spark plugs, faulty ignition system, distributor failure, and more. If you’d like to try to fix code P0305 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Keep in mind this is an intermediate-level diagnosis and repair and not recommended for beginners. Diagnosis requires more specialized equipment beyond what the FIXD Sensor can provide and it can be a time and labor-intensive process for inexperienced DIYers.

DIY difficulty level: Intermediate

This repair requires mechanical knowledge and is not recommended for beginners.

Tools/parts needed (our top picks from Amazon):


Use FIXD to scan your vehicle to verify P0305 is the only code present. If other codes are present, they must be addressed first.


Look for loose engine ground wires as well. These can cause random misfire conditions. Tighten or connect where necessary.


Worn and old spark plug wires are common causes of random misfires. Replace spark plugs and wires if needed and recheck for misfires. 

> How to replace spark plugs in 4 easy steps

> How to identify a fouled spark plug

> How to test spark plug wires

> How to gap spark plugs


If you have determined that your ignition system is operating correctly, there may be a problem within your fuel system that is causing the random misfires. The following should be checked to ensure the engine is getting the proper amount of fuel.

  • Check fuel pressure: Low fuel pressure can cause intermittent misfires on multiple cylinders. When the pressure is below the specification, the engine does not receive the proper amount of fuel and will start to lean misfire. The fuel pump or fuel pressure regulator could be the source of the low fuel pressure.

> How to check fuel pressure

  • Check fuel injectors: Make sure the fuel injectors are functioning properly and activating. Random misfires can be a sign of faulty or clogged fuel injectors that need to be replaced. Also, check that the fuel injector wiring is not damaged and is connected properly.

> How to check fuel injectors by ear

> How to check fuel injectors with a digital multimeter


If the ignition system and fuel system checks out, you may want to perform an engine compression test and leakdown test to see if there are any mechanical problems causing your misfire. 

Common mechanical problems that can cause misfires:

  • Leaking Head Gasket
  • Broken valve spring
  • Broken piston ring
  • Worn valve guides
  • Burned valve
  • Timing chain or belt skipped tooth and engine is off time.

Common P0305 diagnosis mistakes

Loose fitting electrical connectors and broken or disconnected vacuum hoses are often overlooked. Oxygen sensor(s) are another common misdiagnosis for P0305.

Still Need Help Fixing Code P0305?

If you’ve followed the steps above and are still experiencing misfires or check engine code P0305, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.


Recovering autocross and track day enthusiast. Once turned a VW Jetta into a pickup truck. Lives in a van down by the river. Dream car: 2001 Subaru WRC rally car.

Justin Hughes
Recovering autocross and track day enthusiast. Once turned a VW Jetta into a pickup truck. Lives in a van down by the river. Dream car: 2001 Subaru WRC rally car.

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      1. Thanks John! So glad we could help!

        FIXD Team

    5. thank you guys very much good advice i needed to know

    6. I have a cylinder 5 misfire in a 98 Toyota Camry I have replaced the plugs wires crankshaft position sensor coil packs and it just keeps coming right back what could cause this

      1. I’ve changed plugs and coil and injectors are working but still having miss fire on c5.

        1. Did you ever figure out what your problem was, I too have changed the plugs, coils and injectors, don’t compression check but still having miss fire on number 5

    7. FIXD is an automotive education in a tiny package. Thank you for saving me headaches when the “check engine” light comes on in my Acadia.

    8. MISS FIRE CYL #5 My 1996 Toyota needed spark plugs as old plugs had 34K miles. Replaced plugs but still had miss fire on Cyl #5. Toyota 23 yrs old, 182K miles still with original “Ignition Coil on Spark Plugs”. Purchased new “Ign Coil on Plug”, problem solved.

    9. thank you you help me a lot !

      1. I have a misfire on cylinder 5 on my 2001 Ford explorer. I have replaced the plugs, wires, coil and have changed out the fuel filter. I can’t figure out what else would cause it to keep coming back on.

        1. check ur temp sensor..

    10. on my 2004 chevy blazer when i got the po305 code cyl 5 mis fire .. i thought like everyone else great tune up time.. but just did this yr before what could it be??? more digging lead me to the temp sensor right above the cyl 5 dummy test it the next day unpluging it an starting it up on a cold start it dint jump jurk like it was on the first start for the first 5min or so .. changed out the temp sensor runs great getting better gas mile now.. some times it pays off to dig alil to find the heart of the prob. js..

    11. Thanks, cylinder 5 keeps failing on mine too, this is the 5th or so time in 4 years. We are fixing the coil packs now and flogging it. Had enough, I love my car but sick of the repairs. This post has helped heaps

    12. Just made a comment about not knowing once I drop car off at repair shop..until I just watched the video on how to check before taking to the shop! With step by step instructions..OK..FIXD is ultimately awesome!!

      1. Thank you so much, Angela! We appreciate the kind words. Happy and safe driving to you and yours! 🙂

    13. Got the P305 code on my 2007 Honda Pilot with 154,334 miles on original engine. Changed out the spark plugs and coil packs but still getting the same code reading after that! What else should I check?

    14. Just bought your Fixd sensor. Watched your video too. Will ask my son to switch the coils on 5 to 4, since problems seems to be #5 cylinder. Hope that helps me out. We’ll see but video was very informative for me.

      1. Awesome to hear, Barbara! We are so glad your son will be able to help you make a quick, affordable repair. Thank you so much for using FIXD! 🙂

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