P0305 means the powertrain control module (PCM) has detected a misfire on cylinder 5. It identifies the cylinder in which the misfire was detected, not the component that has failed. A faulty ignition coil or spark plug is one possibility, but an injector fault, low compression or a localised vacuum leak may also be responsible. The correct repair follows diagnosis rather than replacing parts on the basis of the code alone.
What does code P0305 mean?
“Cylinder 5 Misfire Detected” means the PCM has detected that cylinder 5 is not firing consistently. Put simply, the air-fuel charge in that cylinder is not igniting properly or reliably. P0305 does not confirm a failed coil, spark plug, injector or internal engine component; it is a diagnostic clue, not a parts-replacement instruction.
Confirm the cylinder numbering for your exact engine before inspecting anything. Cylinder 5 can be in a different physical location depending on the engine layout and manufacturer. For an overview of the code and possible causes, see iCarsoft’s P0305 guide.
Symptoms of a cylinder 5 misfire
A P0305 misfire can cause:
- A rough or uneven idle;
- Engine stumbling, hesitation or shaking;
- Reduced power; and
- A Check Engine Light that may flash under load.
Symptoms vary between vehicles and do not identify the failed part by themselves. Equally, a steady Check Engine Light does not prove that the problem is harmless.
If your scan tool reports P0300 rather than P0305, that is a different code indicating a random or multiple-cylinder misfire. The P0305 evidence discussed here cannot establish the most common cause of P0300. See our separate guide to the P0300 random or multiple-cylinder code for that distinction.
Common and less common causes of P0305
- Ignition coil fault: A failing coil can prevent cylinder 5 from receiving a consistent spark.
- Spark plug condition: A worn, fouled, cracked or otherwise damaged plug can contribute to a misfire.
- Fuel injector issue: A restricted, clogged or faulty injector is another possible cause, but it should be tested rather than assumed to be at fault.
- Low compression: An internal mechanical issue that reduces compression in cylinder 5 can produce a persistent misfire.
- Localised vacuum leak: An air leak affecting the area serving the affected cylinder can also contribute to a misfire.
Ignition components are sensible early checks, but P0305 alone cannot rank these causes for an individual vehicle. If basic ignition checks do not explain a continuing misfire, further testing is more useful than repeatedly swapping or buying parts. For broader background, read our guide to cylinder misfire causes and fixes.
How to diagnose a P0305 misfire step by step
- Confirm the code and identify cylinder 5. Use a scan tool to confirm P0305 and check for any additional fault codes that may provide useful context. Then use vehicle-specific service information to verify cylinder numbering.
- Inspect accessible ignition components. With the engine switched off, inspect accessible wiring, connectors and ignition components around cylinder 5 for visible damage, loose connections or signs of arcing. Access procedures and ignition-system design vary by vehicle.
- Use a coil swap test only on a suitable coil-on-plug system. If the vehicle uses individual, interchangeable coil-on-plug units, move the cylinder 5 coil to a neighbouring cylinder, clear the code and recheck the fault after the engine has run. If the misfire moves to the cylinder that received the coil, that supports a faulty coil. If P0305 remains, the test has not identified that coil as the cause; it does not prove that every ignition component is sound. Do not attempt this test on a system not designed for it.
- Inspect the spark plug. If the plug can be removed safely and you are competent to do so, check it for fouling, cracks, worn electrodes and oil on the threads. Compare it with plugs from other cylinders where appropriate. Any replacement plug must match the manufacturer-specified type, gap and heat range; do not rely on a generic recommendation.
- Evaluate the injector if the misfire remains. Injector assessment may include checking for operation and measuring resistance against the vehicle manufacturer’s specification. These tests require correct service data and suitable competence. A suspected restricted injector is not the same as a confirmed injector failure.
- Escalate to mechanical and air-leak testing. If ignition and fuel checks do not resolve the fault, a technician may need to carry out compression testing and investigate for a vacuum leak local to the affected cylinder.
Autobarn’s P0305 diagnostic overview also describes checking suitable ignition components. Treat component swapping as a diagnostic method, not as a universal repair procedure: access, ignition design and test methods depend on the vehicle and engine.
How to fix code P0305
Fix the cause confirmed by testing. If a compatible coil swap shows that the misfire follows the coil, replace the faulty unit with an OEM or OE-equivalent part. Inspect the coil boot for arcing tracks and replace the boot as well if it is damaged and separately serviceable.
If inspection and testing identify a faulty spark plug, fit the specified plug with the correct gap and heat range. If testing points to an injector problem, professional cleaning may be appropriate in some cases before replacement is considered. A replacement injector must be fitted and reseated according to vehicle-specific service information, including a new O-ring where applicable.
If testing indicates low compression or a localised vacuum leak, the repair must address that underlying fault. Replacing a coil or injector will not correct a mechanical or air-leak problem. After any repair, clear or recheck the codes as appropriate and assess how the engine runs. If P0305 or the misfire returns, arrange professional diagnosis rather than continuing to replace unconfirmed parts. Edmunds’ P0305 repair overview also lists spark plugs, ignition coils and damaged components among possible repair areas.
Can you drive with a P0305 code?
The code by itself cannot establish whether the vehicle is safe to drive or how severe the fault is. If the Check Engine Light is flashing, the engine is shaking severely, power is substantially reduced or the vehicle is otherwise running abnormally, stop in a safe place and arrange prompt professional assistance or recovery.
If the light is steady and symptoms are mild or absent, that is still not a guarantee that continued driving is safe. Arrange prompt diagnosis and minimise unnecessary driving until the cause is known. For a related cylinder-specific discussion, see what to do about a cylinder 4 misfire; that article does not determine whether a vehicle showing P0305 is safe to drive.
How much does it cost to repair a cylinder 5 misfire?
iCarsoft gives a rough $20–$200 DIY estimate for common spark-plug or ignition-coil repairs. This is a limited source-reported figure for DIY work, not a guaranteed total, workshop quote or estimate for every P0305 cause.
The final cost depends on what diagnosis confirms, the parts required, labour, engine layout and access, and whether injector or mechanical diagnosis and repair are needed. Diagnosing the fault before purchasing parts can help avoid paying for a component that was not causing the misfire. For related context, see our guide to cylinder 1 misfire repair costs; it is not a quote for your vehicle or fault.
Does the P0305 fix differ by vehicle?
The general diagnostic logic applies to a Chevrolet or Silverado, Ford or Nissan: identify cylinder 5 correctly, check relevant ignition components and the spark plug, then investigate injector, compression and air-leak causes if the misfire remains. However, the available information does not establish a make-specific repair or a particular common failure for those vehicles. Likewise, the search wording “chevy silver” does not identify a particular model, year or engine.
Cylinder location, component access, ignition design, replacement parts and specifications all depend on the exact year, model and engine. Check vehicle-specific service information before following a procedure, and provide those details to a technician. Do not assume that a repair shown for one Silverado, Ford or Nissan applies to another. Owners of the relevant Charger models can also consult the Dodge Charger-specific cylinder 5 misfire guide, which applies only to the stated Charger context and not to other makes or engines.