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.

Reading P0300 on a Ford properly

A generic reader will show P0300 and nothing else. What matters is the freeze-frame data stored with it — engine speed, load, coolant temperature and fuel trims at the moment the fault was logged — plus whether any other module on the Ford has logged something at the same time. Codes rarely arrive alone, and the order they were stored in usually points at which one is the cause and which are the consequences.

Clearing P0300 without fixing it

Erasing the code resets the Ford's readiness monitors as well as the light. The fault returns on the next drive cycle if the cause is still there, and in the meantime the incomplete monitors can stop the car passing an emissions check. After a genuine repair, the car is driven until the relevant monitor completes before it is handed back.

Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0300 is showing on your Ford, bring any scan results with you — we will read the live data ourselves, confirm which cause it actually is, and price the repair before any work starts.