P0300 Fault Code on BMW 3 Series — UK Guide (2005–2015)

P0300 on the BMW 3 Series — what you need to know

BMW 3 Series P0300 random misfire is common on the N46 and N52 petrol engines. Spark plug failure and faulty ignition coils are the most frequent causes. BMW spark plugs should be replaced every 40,000 miles.

The affected engine variants are: 316i, 318i, 320i, 325i. If your BMW 3 Series is showing fault code P0300, use our AI Diagnostic Report for a full UK-specific analysis including the exact repair costs for your engine and year.

Common causes on the BMW 3 Series

While P0300 can have several root causes, the most common reasons this code appears on the BMW 3 Series in UK conditions are related to the specific engine management and emissions systems fitted to this vehicle. Always scan for related fault codes before replacing any parts — a secondary code can point directly to the root cause and save hundreds of pounds.

For the complete diagnosis guide including step-by-step testing procedures, see our main P0300 fault code page.

UK repair costs for P0300 on the BMW 3 Series

Typical UK repair costs for P0300 on the BMW 3 Series range from £80 to £500 depending on the exact cause, your engine variant and whether you use an independent garage or a main dealer. Independent garages are typically 30–50% cheaper than franchised dealers for this type of repair.

Always get at least two quotes. Use our AI Diagnostic Report to understand the most likely cause for your specific BMW 3 Series before spending anything at a garage.

P0300 MOT implications for the BMW 3 Series

An active P0300 fault code on your BMW 3 Series is likely to cause an MOT failure. Under DVSA testing standards, an illuminated check engine light is an automatic MOT failure regardless of how the vehicle drives. You must resolve this fault before your MOT test. Read our full MOT guide for more information.