Cylinder 5 Misfire Detected
In short
P0305 means your engine's computer detected a misfire in cylinder number 5 — that cylinder isn't burning its air-fuel mixture properly on every combustion cycle. The most common real-world cause is a worn spark plug or a failing ignition coil on that specific cylinder. It usually shows up as a rough idle, a flashing or steady check engine light, and sometimes a noticeable loss of power.
Is it safe to drive with P0305?
Short, gentle drives are usually fine if the check engine light is steady, but a misfire dumps unburned fuel into the exhaust and can overheat and destroy the catalytic converter over time. If the light is flashing, that signals an active, damaging misfire — pull over when safe, avoid hard acceleration, and get it fixed promptly.
Symptoms
- Rough or shaky idle, especially right after a cold start
- Check engine light on steady, or flashing during the misfire
- Noticeable loss of power or hesitation under acceleration
- Engine vibration felt through the steering wheel or seat
- Increased fuel consumption and occasional fuel smell from the exhaust
- Stumbling, sputtering, or popping sounds from the engine
Common causes (most → least likely)
How to diagnose it (before buying parts)
- 1 Scan all stored codes first — note whether other cylinder misfire codes (P0301-P0308) or a random misfire (P0300) are present, plus any lean/rich or fuel-trim codes that point to a root cause.
- 2 Check live data and freeze-frame: look at misfire counts per cylinder and note the conditions (cold, idle, load) when the misfire occurred.
- 3 Locate cylinder 5 using the engine's firing/cylinder layout, then visually inspect that coil, plug boot, and wiring for cracks, oil, corrosion, or a loose connector.
- 4 Swap the cylinder 5 ignition coil (and plug) with a known-good neighboring cylinder, clear the code, and drive — if the misfire follows the part to the new cylinder, you've found the culprit.
- 5 If the misfire stays on cylinder 5, perform a compression or leak-down test and check injector operation before condemning any parts.
Repair options & cost
By manufacturer
On V6 engines the rear bank (which often includes cylinder 5) is harder to reach; coil-on-plug failures and aging iridium plugs are frequent triggers for single-cylinder misfire codes.
V6 models are prone to coil-on-plug breakdown causing one-cylinder misfires; carbon buildup on direct-injection intake valves can also contribute on higher-mileage engines.
Coil-on-plug units and worn plugs are common P0305 causes; on some engines a failed coil can crack the plug boot, so inspect both together.
Ignition coil packs are a well-known weak point and often fail in batches; replacing all coils and plugs as a set is a common fix when one cylinder misfires.
Frequently asked questions
Can I drive with a P0305 code?
You can usually drive short distances if the check engine light is steady, but you risk damaging the catalytic converter the longer the misfire continues. If the light is flashing, stop hard acceleration and get it fixed right away to avoid expensive converter damage.
Where is cylinder 5 located?
Cylinder 5 isn't always the fifth one you see — its position depends on your engine's cylinder numbering. Check a firing-order or cylinder-layout diagram for your specific make and engine, often found in the service manual or a sticker under the hood.
How much does it cost to fix P0305?
The most common repairs — a spark plug or ignition coil — typically run about 15 to 400 dollars depending on DIY versus shop labor. If the cause is a fuel injector or internal engine damage, costs can climb to several hundred or even a few thousand dollars.
Will a misfire fix itself or clear on its own?
A misfire generally won't fix itself; the underlying part needs attention. The code may clear temporarily if conditions improve, but it will return until the worn plug, coil, injector, or mechanical issue is repaired.