SevereAffected: 2012-201860,000–120,000 miles

Ford Fiesta Mk7 1.0 EcoBoost 100bhp — Coolant Loss from Cylinder Head

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.

Severity

Severe

DIY Difficulty

Hard

Est. Cost

£500–£900

OBD Codes

P0217P0128

Component Diagram

Cooling

Typical layout and location for the Cooling assembly.

Reference Illustration

Symptoms

Coolant reservoir dropping without visible leak
Sweet smell from engine bay
White steam from exhaust on startup
Overheating warning
Heater blowing cold intermittently

Root Cause

Heat from the integral exhaust manifold causes repeated thermal cycling of the head gasket. On high-mileage examples the gasket fails between the water jacket and combustion chamber. Some early engines also had a casting defect in the coolant passage.

How To Fix

Pressure test the cooling system to confirm loss
Check for combustion gases in coolant with a block tester kit (yellow turns green = positive)
Replace head gasket — requires camshaft and VCT removal
Inspect head for warping before refitting
Fit an upgraded MLS (Multi-Layer Steel) head gasket if available

Estimated Repair Costs

Repair Option	Est. Cost (GBP)
DIY (parts only)	£200–£360
Independent Garage	£500–£900
Main Dealership	£800–£1440

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.

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.

Clutch Wear and Judder on Engagement

Moderate

2012-201850,000–90,000 miles£400–£700

The lightweight flywheel and small clutch on the 1.0 EcoBoost are undersized for the turbo torque. Clutch wear and judder on biting point is common from 50,000 miles, especially in urban use.

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