P0300 on Ford: Causes, Symptoms and Fix Cost
Quick Answer
Not safe to drive
P0300 on a Ford means the engine computer has detected misfires across several cylinders without being able to pin them to one specific cylinder, so it flags the whole engine rather than a single cylinder. The most common trigger is worn or fouled spark plugs that no longer spark reliably, and a full set costs about 60 to 230 EUR fitted. A steady light is a warning, but a flashing light means raw fuel is reaching the catalytic converter, so stop driving.
- Severity
- High · Misfire
- Typical repair cost, all makes
- €60-€700
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your Ford and Skanyx tells you what P0300 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat does P0300 mean on a Ford?
The Quick Answer above is the generic definition. What follows is the model-specific detail for the Ford models that log P0300.
Ford Focus
2011-2024
The 1.0 EcoBoost three-cylinder is sensitive to spark plug and coil wear, and because it has only three cylinders a single weak coil quickly reads as a multi-cylinder misfire. Degraded ignition leads and coil-on-plug boots are common on older 1.6 and 2.0 engines. Coolant intrusion issues on some early EcoBoost units can also foul plugs, so check the cooling system if plugs and coils do not solve it.
What causes P0300 on a Ford?
Beyond the generic causes listed on the main P0300 page, these are the patterns noted for Ford models:
Spark plug and ignition coil wear on the 1.0 EcoBoost three-cylinder
: Ford Focus
Worn coil-on-plug boots and leads on 1.6 and 2.0 engines
: Ford Focus
How to diagnose P0300 on a Ford with OBD2
- Scan for companion codes (P0301 to P0312). If a cylinder-specific code is also stored, start with that cylinder before treating P0300 as a whole-engine fault
- Inspect the spark plugs for wear, oil or carbon fouling, and a worn electrode gap. Replace the full set if they are past the maker's service interval or if several look fouled
- Test the ignition coils, swapping one coil to a different cylinder to see if the misfire follows it, or measuring resistance with a multimeter against spec
- Smoke-test the intake for vacuum leaks, or spray carb cleaner around the intake manifold gasket and hoses and listen for an idle change
- Check fuel pressure with a gauge. It should hold steady at the maker's spec, typically around 2.8-4.1 bar (40-60 psi) on port-injection engines, and not drop under load
- Inspect the EGR valve for sticking and check intake valves for carbon on direct-injection engines, then run a compression or leak-down test if everything else checks out
How much does P0300 cost to fix on a Ford? (EUR)
Estimated repair costs for P0300 in EUR, compiled across makes. Ford parts and labour usually land towards the lower end of each range.
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace spark plugs (full set) | €20–€80 | €40–€150 | €60–€230 | Easy |
| Replace ignition coil(s) | €30–€200 | €40–€120 | €70–€320 | Moderate |
| Fix vacuum leak | €10–€80 | €60–€200 | €70–€280 | Moderate |
| Replace fuel injectors | €100–€400 | €100–€300 | €200–€700 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P0300
These codes are often seen alongside P0300 or point to related issues, on any make:
Looking for the full P0300 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0300 guide