Ford P0300

Random misfire on Ford petrols — on EcoBoost engines almost always coils or low-tension wiring, on Duratec usually plugs at end of life.

Ford P0300 — Random misfire on Ford petrols — on EcoBoost engines almost always coils or low-tension wiring, on Duratec usually plugs at end of life. Typical UK independent garage cost: £80–£380.

What actually causes P0300 on a Ford

On the 1.0 EcoBoost a single failing coil pack often logs P0300 first (random) rather than a specific cylinder, because the misfire pattern moves between cylinders as load changes. Coil-on-plug units crack around the boot. On 1.6/2.0 EcoBoost worn iridium plugs (90k+ miles) and a known coil-pack heat-soak issue under the supercharger area cause hard-to-pin-down random misfires. On Duratec it's almost always overdue spark plugs.

Ford engines that log P0300

• 1.0 EcoBoost (Fiesta, Focus, B-Max, EcoSport)
• 1.6 EcoBoost (Focus, Kuga)
• 2.0 EcoBoost (Mondeo, Kuga, Edge)
• 1.6 Ti-VCT / Duratec

How we diagnose P0300 on a Ford

1. FORScan or generic OBD — read per-cylinder misfire counters (PIDs $E5–$E8) at idle and 2,500 rpm
2. Swap-test a suspect coil between cylinders — if misfire follows the coil, that's your part
3. Pull plugs and inspect — iridium plugs over 80k miles on EcoBoost are routinely worn out
4. Inspect coil boots for hairline cracks — common heat-fatigue failure
5. On 1.0 EcoBoost, exclude head/manifold coolant leak (P0171/oil contamination check) before chasing ignition

The common misdiagnosis to avoid

Don't accept a 'replace all 4 coils + plugs' £300+ quote until per-cylinder misfire counters have been read with a live scan tool. Often a single £55 coil and a £40 set of plugs clears it.

Ford P0300 repair cost in the UK

Expect £80–£380 including parts and labour at an independent garage. Main-dealer quotes on Ford are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.

Bob's workshop tip

On 1.0 EcoBoost, always use Motorcraft or Bosch plugs to the exact Ford spec — wrong heat range and you'll be back in 6 months. Don't fit cheap multi-fit plugs to these engines.

Codes usually seen alongside P0300 on Ford

• P0301
• P0302
• P0303
• P0304
• P0171

Symptoms drivers report with P0300

• The car feels like it's 'kangaroos' down the High Street when you're in a high gear at low revs.
• The engine management light isn't just on; it's flashing at you like a disco light—that means 'stop now or kill the cat'.
• It idles like a bag of spanners when you're sat at the traffic lights, making the whole dashboard shake.
• A heavy smell of unburnt petrol from the exhaust, especially on cold starts.
• Huge flat spot when you try to overtake on the A9; the power just goes missing.

Repairs that clear P0300

• Replace spark plugs and ignition coils
• Test fuel injectors
• Check timing
• Compression test if persistent

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0300 guide.