P0300 on Hyundai: Causes, Symptoms and Fix Cost

Quick Answer

Not safe to drive

P0300 on a Hyundai 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 Hyundai 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.

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What does P0300 mean on a Hyundai?

The Quick Answer above is the generic definition. What follows is the model-specific detail for the Hyundai models that log P0300.

Hyundai Santa Fe

2006-2024

On Hyundai GDI engines (i30, Tucson, Santa Fe, Kona), a random P0300 usually comes from worn ignition coils or spark plugs, or from carbon on the intake valves of the direct-injection units. Rule out coils and plugs first, then check for carbon. If the engine also uses oil or knocks under load, stop and have the bottom end assessed before spending anything on ignition parts.

What causes P0300 on a Hyundai?

Beyond the generic causes listed on the main P0300 page, these are the patterns noted for Hyundai models:

Worn ignition coils or spark plugs past 100,000 km
: Hyundai Santa Fe
Intake-valve carbon build-up on direct-injection GDI engines
: Hyundai Santa Fe

How to diagnose P0300 on a Hyundai with OBD2

Follow these steps to pinpoint the root cause of P0300:

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 Hyundai? (EUR)

Estimated repair costs for P0300 in EUR, compiled across makes. Hyundai costs typically sit in the middle 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 March 2026. Costs vary by region, vehicle, and shop.

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

Diagnose P0300 on your Hyundai

Your car logged P0300. Skanyx reads it on a standard OBD2 adapter (Bluetooth LE on iPhone), tells you whether it is safe to keep driving, and shows the €60-€700 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.