P0305
PowertrainCylinder 5 Misfire Detected
Cylinder 5 is misfiring. This code only appears on engines with five or more cylinders, V6s, V8s, V10s, and the odd inline-five.
ⓘ Information only. This page provides general educational information about fault code P0305. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0305 mean?
P0305 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 5 Misfire Detected.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light, often flashing under load if the misfire is severe
- • Rough idle, sometimes more obvious in gear with the brake on
- • Lumpy power delivery, particularly noticeable on the motorway
- • Worse fuel economy
Possible causes
Causes commonly associated with P0305, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Spark plug for cylinder 5 worn, fouled, or with the wrong gap
- 2. Failed coil-on-plug unit
- 3. Injector blocked or sticking
- 4. On V6/V8 engines, cylinder 5 is sometimes harder to access; loose connectors after past service work are common
- 5. Compression issue, worn rings, valve, or head gasket on that cylinder
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. On a V engine, work out which bank cylinder 5 lives on. Numbering varies, Ford V8s do 1-3-5-7 down one bank, GM does 1-3-5-7-9 down the other. Get this right before pulling parts
- 2. Inspect the plug, coil, and injector connector for cylinder 5
- 3. Coil swap test with a healthy cylinder
- 4. Check fuel trims for that bank, lean readings on bank 1 with P0305 typically points to fuel or vacuum, not ignition
- 5. Compression test if everything else checks out clean
Common questions about P0305
Which bank is cylinder 5 on my engine? +
It depends on the manufacturer. Ford and Chrysler typically number all odd-numbered cylinders down one bank, all even down the other. GM and most German manufacturers number front-to-back on each bank. Always check a workshop diagram for your specific engine before assuming.
Can I just clear the code and see if it returns? +
You can, but a misfire severe enough to set a cylinder-specific code rarely fixes itself. The underlying cause is mechanical or electrical and won't resolve on its own. Driving with a flashing warning light risks the catalytic converter.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →