ModerateAffected: 2012-201750,000–100,000 miles

Ford Fiesta Mk7 1.0 EcoBoost 100bhp — Ignition Coil Pack Failure

Coil packs break down internally with heat and age, causing severe misfires under load.

Severity

Moderate

DIY Difficulty

Easy

Est. Cost

£50–£150

OBD Codes

P0300P0301P0302P0303P0304

Component Diagram

Engine

Typical layout and location for the Engine assembly.

Reference Illustration

Symptoms

Engine hesitates and jerks when accelerating hard
Flashing EML light during misfire
Rough, lumpy idle
P0301-P0304 fault codes

Root Cause

The insulation inside the pencil coil breaks down due to engine heat. The spark then jumps to the cylinder head instead of crossing the spark plug gap.

How To Fix

Read OBD codes to identify which cylinder is misfiring (e.g., P0302 = Cyl 2).
Swap the coil pack to another cylinder and re-read codes to confirm the coil is at fault.
Replace coil pack (£30-60 each).
Advised to replace spark plugs at the same time.

Estimated Repair Costs

Repair Option	Est. Cost (GBP)
DIY (parts only)	£20–£60
Independent Garage	£50–£150
Main Dealership	£80–£240

Other Faults on This Variant

Timing Chain Stretch and Tensioner Failure

Critical

2012-201540,000–100,000 miles£600–£1200

Pre-2016 Ford 1.0 EcoBoost engines suffer from premature timing chain stretch. The plastic tensioner can fail, causing catastrophic engine damage with little warning.

Coolant Loss from Cylinder Head

Severe

2012-201860,000–120,000 miles£500–£900

The 1.0 EcoBoost has an integrated exhaust manifold cast into the cylinder head. This design causes head gasket stress and coolant loss, sometimes causing overheating.

Thermostat Failure and Overheating Risk

Moderate

2012-201850,000–100,000 miles£80–£180

The plastic thermostat housing on the 1.0 EcoBoost is prone to cracking. A stuck-open thermostat causes the engine to run cold and burn more fuel; a stuck-closed thermostat causes rapid overheating.

Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.