OBD-II Code · Powertrain
P0305
Cylinder 5 Misfire Detected
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Depends on the light
Flashing: stop as soon as it is safe to — raw fuel is reaching the catalytic converter. Steady, and it only feels rough: a short drive to a shop is usually fine. Either way, stop if it shakes hard, loses power, overheats or makes a new noise.
Indicative cost (USD)
$30–$400
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Plug/coil first
Cylinder 5 misfire. V6/V8 engines only.
How a shop works this
The ECU has already told you which cylinder. That makes the fastest honest test a swap: move one part to another cylinder and see whether the fault moves with it. It identifies the fault instead of guessing at it, and it costs nothing.
Photograph the coils before you touch anything, and note which is which.
Cylinder numbering is not the same across manufacturers, and V6 and V8 bank layouts differ by maker — look up the firing order and bank layout for your engine before you move parts, or you can spend an hour swapping coils on the wrong bank.
Move the cylinder 5 ignition coil to a cylinder that is not misfiring, put that cylinder's coil on 5, clear the code, and run it until the misfire returns.
On a modern coil-on-plug engine the coil is the most common single answer to a cylinder-specific misfire, which is why it is the first thing to move — not because it is the cheapest part. A misfire that is there even at idle is the classic dead-coil pattern.
- The misfire follows the coil to its new cylinderThe coil is the fault. Replace it. If the engine has real mileage on it, the other coils are on the same clock.
- The misfire stays on cylinder 5The coil is fine. Look at the coil connector and the harness around it next — chafed and rodent-damaged connections at that plug are a common second answer — then pull the plug.
Read the plug you pulled, and check the boot for carbon tracking.
Black and sooty means it has been running rich. White or blistered means lean or too hot. Oil-wet points at valve seals or rings. Fuel-wet points at an injector holding open. A carbon-tracked boot arcs to the head and imitates a dead coil for the price of a new boot. On an older engine with a distributor, the cap, rotor and plug wires belong in this step too.
If spark is accounted for, go to fuelling, then to compression.
An injector balance or flow test comes first because it is quicker. Compression test second: a cylinder more than about 15% below its neighbours is mechanical, and no ignition part will fix it. A vacuum leak on this one runner sits alongside these — a leak big enough to affect every cylinder would be setting P0300 instead.
A flashing check-engine light means the misfire is putting raw fuel into the catalytic converter, which can destroy it quickly. Stop driving as soon as it is safe to. A steady light with a mild misfire is less urgent, but stop anyway if it shakes hard, loses power, overheats, or makes a noise it was not making before.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Rough idle
- Check engine light
- Engine vibration
Likely causes
- Failed ignition coil (cylinder 5)Most common
- Damaged coil connector or harness at cylinder 5
- Worn spark plug or carbon-tracked boot (cylinder 5)
- Clogged or leaking fuel injector (cylinder 5)
- Low compression on cylinder 5
- Vacuum leak at the cylinder 5 intake runner
Read the full diagnostic procedureP0305 means cylinder 5 is misfiring, which only exists on engines with 5 or more cylinders — so you're looking at a 5-cylinder inline (Audi/VW 2.5L,…
P0305 means cylinder 5 is misfiring, which only exists on engines with 5 or more cylinders — so you're looking at a 5-cylinder inline (Audi/VW 2.5L, Volvo white-block, GM Atlas), an inline-6, a V6, a V8, or a V10. The diagnostic flow is the standard misfire drill (plug read, coil swap, plug swap, compression, injector balance), but cylinder identification matters more than on a 4-cylinder. On a Ford 5.4L 3-valve V8, cylinder 5 is the front-most cylinder on the left (driver's) bank. On a GM LS-series V8, cylinder 5 is the second cylinder from the front on the left (driver's) bank. On a Chrysler 5.7L Hemi, cylinder 5 is the front-most cylinder on the left bank. On a transverse Chrysler 3.6L Pentastar V6, cylinder 5 is the middle cylinder of the right bank. Get the FSM cylinder map before you start swapping or you'll burn 30 minutes on the wrong COP coil.
Vehicle-specific patterns2004-2008 Ford F-150/Expedition with the 5.4L 3V Triton is the king of P0305 — the 3-valve cylinder heads have a well-documented stuck-spark-plug iss…
- 2004-2008Ford F-150/Expedition with the 5.4L 3V Triton is the king of P0305 — the 3-valve cylinder heads have a well-documented stuck-spark-plug issue (carbon welds the plug to the head) and the cam-phasers fail and rattle, both of which manifest as misfires on the left-bank cylinders 5/6/7/8.
- 2005-2010Volvo XC90/S60 with the 2.5T inline-5 commonly throws P0305 from a failed ETM (electronic throttle module) creating uneven air distribution; the rear cylinders see it first.
- 2003-2009Audi/VW 2.0T (BPY, BWT) and the 2.5L five-cylinder (Jetta, Beetle) frequently throws P0305 from coil-pack failures that hit one cylinder at a time — Audi/VW typically warranty-replaced the whole set.
Estimated repair$40 (single coil) to $2,200+ (cam phasers on the 5.4L 3V).
Look up another code
P0305 — frequently asked
What does a P0305 code mean?
Cylinder 5 misfire. V6/V8 engines only.
What causes a P0305 code?
Common causes: Failed ignition coil (cylinder 5); Damaged coil connector or harness at cylinder 5; Worn spark plug or carbon-tracked boot (cylinder 5); Clogged or leaking fuel injector (cylinder 5); Low compression on cylinder 5; Vacuum leak at the cylinder 5 intake runner.
What are the symptoms of a P0305 code?
Typical symptoms: Rough idle; Check engine light; Engine vibration.
Is it safe to drive with a P0305 code?
Depends on the light. Flashing: stop as soon as it is safe to — raw fuel is reaching the catalytic converter. Steady, and it only feels rough: a short drive to a shop is usually fine. Either way, stop if it shakes hard, loses power, overheats or makes a new noise. Estimated repair: $30-$400 — plug/coil first.
How do I diagnose a P0305 code?
The ECU has already told you which cylinder. That makes the fastest honest test a swap: move one part to another cylinder and see whether the fault moves with it. It identifies the fault instead of guessing at it, and it costs nothing. 1. Photograph the coils before you touch anything, and note which is which. 2. Move the cylinder 5 ignition coil to a cylinder that is not misfiring, put that cylinder's coil on 5, clear the code, and run it until the misfire returns. 3. Read the plug you pulled, and check the boot for carbon tracking. 4. If spark is accounted for, go to fuelling, then to compression.
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