Fault code P0306 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0306 – Cylinder 6 Misfire Detected

P0306: Causes, signs and repairs

Error code P0306 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected misfiring in the sixth cylinder. This DTC P0306 fault code indicates that the combustion process in cylinder 6 is not working properly, resulting in incomplete combustion and increased emissions.

What can cause this fault code?

Defective spark plug in cylinder 6
Damaged ignition coil or ignition cable
Blocked or defective injection nozzle
Low compression in the sixth cylinder
Defective cylinder head gasket
Dirty or defective lambda sensor
Clogged fuel filter
Low fuel pressure
Defective valves or valve guides
Loose or corroded plug connections

What symptoms occur in parallel with fault code P0306?

Engine unsteadiness: Noticeable jerking and uneven engine running at idle and under load
Loss of power: Significantly reduced engine power, especially when accelerating
Increased fuel consumption: Measurably higher consumption due to incomplete combustion
Starting problems: Difficult starting, especially when the engine is cold
Exhaust odor: Unburned fuel can be detected in the exhaust gas
Knocking noises: Metallic noises from the engine compartment

How can the problem with error code P0306 be rectified?

Repairing trouble code P0306 requires a systematic diagnosis to identify the exact cause.
Spark plug replacement: Check all spark plugs and replace defective ones, ensuring correct heat value and electrode gap
Ignition coil repair: Test the ignition coil of cylinder 6 and replace if defective, including checking the electrical connections
Injector cleaning: Professional cleaning or replacement of the fuel injector in cylinder 6 if clogged or defective
Compression check: Measure cylinder compression and repair valves, piston rings or cylinder head gasket if values are low
Fuel system maintenance: check fuel filter and fuel pump, replace if necessary and measure fuel pressure
Engine diagnostics: complete engine analysis with professional OBD scanner and repair of mechanical defects

FAQ - Frequently asked questions about DTC P0306

Can I continue driving with error code P0306?

It is possible to drive for a short time, but you should have the error code P0306 rectified as quickly as possible. Prolonged driving can lead to catalytic converter damage and increased fuel consumption.

How much does it cost to repair error code P0306?

The costs vary depending on the cause: spark plug replacement €50-150, ignition coil replacement €100-300, injector cleaning €150-400. Mechanical engine damage can incur costs of €500-2000.

How do I know whether code P0306 has really been rectified?

After the repair, delete the fault memory and carry out a test drive. The eobd code should no longer occur and the engine should run smoothly.

Can I repair error code P0306 myself?

Simple work such as changing spark plugs is possible, but more complex diagnoses require professional equipment. If you are unsure, you should visit a workshop.

How long does it take to repair DTC P0306?

Between 1-6 hours, depending on the cause: Spark plug replacement 1-2 hours, ignition coil replacement 2-3 hours, more extensive engine work can take a whole day.

Does fault code P0306 occur more frequently in certain weather conditions?

Yes, ignition problems can occur more frequently in damp conditions. Existing defects in ignition components can also worsen in extreme cold or heat.

Vehicles in which fault code P0306 occurs most frequently

Error code P0306 is a standardized OBD-II code for misfiring in the sixth cylinder and can occur in all vehicles with at least six cylinders, but is most common in the following vehicles:

BMW: 3 Series (E46, E90), 5 Series (E39, E60), X5 (E53, E70), 7 Series (E38, E65) (1998-2015)
Mercedes-Benz: C-Class (W203, W204), E-Class (W211, W212), S-Class (W220, W221), ML-Class (W163, W164) (2000-2016)
Audi: A4 (B6, B7, B8), A6 (C5, C6, C7), A8 (D2, D3, D4), Q7 (4L) (1999-2017)
Volkswagen: Passat (B5, B6, B7), Touareg (7L, 7P), Phaeton (3D) (2001-2014)
Ford: Mustang (S197, S550), F-150 (P2, P3), Explorer (U251, U502) (2005-2018)
Chevrolet: Camaro (5th generation), Corvette (C6, C7), Silverado (GMT900, K2XX) (2008-2019)
Nissan: 350Z (Z33), 370Z (Z34), Maxima (A34, A35), Murano (Z50, Z51) (2003-2016)
Toyota: 4Runner (N280), Tundra (XK50, XK60), Sequoia (XK60, XK80) (2007-2020)

If the code P0306 occurs in your vehicle, prompt diagnosis is important, as misfiring not only impairs engine performance, but can also lead to costly consequential damage to the catalytic converter. Most modern vehicles with V6 or V8 engines are affected by this fault code, although older models are more frequently affected due to wear and tear.

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