P0305 code: Cylinder 5 Misfire Detected
P0305 means cylinder 5 Misfire Detected. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0305 means
A misfire means a cylinder isn't burning its air-fuel mixture properly. P0305 points to one specific cylinder — number 5 — which makes it easier to diagnose than a random misfire. The usual cause is that cylinder's spark plug or ignition coil; a quick test is to swap the coil or plug with a neighboring cylinder and see if the misfire follows. Less commonly it's a clogged or dead fuel injector, or low compression in that cylinder from a valve or ring problem. Because unburned fuel can overheat the catalytic converter, a steady misfire shouldn't be left for long.
P0305 symptoms
- Rough idle or shaking, often felt at a stop
- Loss of power or hesitation under acceleration
- Flashing check-engine light during an active misfire
- Reduced fuel economy
- Engine may stumble or be hard to start
What it costs to fix P0305
Typical range: $80–$600 · about ~0.3–3 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Spark plug (single) | $4–$30 | ~0.3–1.5 hrs |
| Ignition coil (single) | $30–$150 | ~0.3–1 hrs |
| Fuel injector (single) | $100–$400 | ~1–3 hrs |
A single plug or coil is the cheap, common fix; an injector is pricier; low compression (a valve or ring issue) is a major repair that varies too much to quote — get it diagnosed if plug, coil, and injector all check out.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0305 for my exact vehicle →
How to fix P0305
Moderate — doable at home with common tools and patience
- Locate cylinder 5 — layout matters here
P0305 only exists on engines with five or more cylinders, and on many transverse V6s cylinder 5 sits on the rear bank tight against the firewall. Find it on a diagram first and honestly assess whether you can reach the coil before committing to the job.
- Run the coil-swap test on cylinder 5
If access allows, exchange coil 5 with one from the easier-to-reach front bank, clear the code, and drive. A code that follows the coil means replace coil 5; a code that stays on cylinder 5 means the coil isn't the problem.
- Examine the cylinder 5 spark plug
Pull plug 5 while the coil is out and look for wear, fouling, or a cracked insulator. If the plugs are original at high mileage, replace the whole rear bank while you have access — you don't want to open this area twice.
- Evaluate injector 5
Listen for injector 5's click, or check its resistance with a multimeter against a known-good injector on the same engine. An open or badly out-of-range reading points to the injector.
- Compression-test or hand it off
Persistent misfire with good spark and fuel on cylinder 5 warrants a compression test. Low compression, or simply no room to work, is the point where a shop earns its money.
DIY or shop? Whether this is DIY depends almost entirely on where cylinder 5 lives: front-bank or inline-engine access makes it an easy afternoon, while a rear-bank cylinder on a transverse V6 can require removing the upper intake manifold — a job with gaskets, torque sequences, and real consequences if rushed. Do the scan and whatever swap tests you can reach yourself; leave intake-off work to a shop unless you're experienced.
Tools for the DIY steps: OBD-II scanner · Spark plug socket with swivel extension · Ratchet and long extensions · Multimeter · Torque wrench
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0305.
Start a case with P0305 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0305?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0305: common questions
Can I drive with P0305?
The code can't answer that by itself. With a steady (not flashing) light, get it looked at soon. If the light is flashing, the active misfire is dumping raw fuel into the catalytic converter and can destroy it; stop driving and have the car towed.
How do I know if it's the coil or the spark plug?
Swap cylinder 5's coil (or plug) with a neighboring cylinder and clear the code. If the misfire moves to the other cylinder, the part you moved is the culprit — a cheap way to avoid replacing the wrong thing.
How much does it cost to fix P0305?
Often modest — a single spark plug or coil is the common, inexpensive fix. It rises if the cause is a fuel injector, and a compression problem (valve or ring) is a major repair that varies widely. Confirm the cause before spending.
Should I replace all the coils or just cylinder 5?
If only cylinder 5 is misfiring, replacing just its coil/plug is reasonable. Some owners replace all of them at once if the parts are old and high-mileage, to avoid chasing the next one — but it isn't required to fix P0305.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0305 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0305 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.