SevereAffected: 2011-201860,000–120,000 miles

Ford Focus Mk3 1.0 EcoBoost 125bhp — Coolant Loss from Integrated Exhaust Manifold

The 1.0 EcoBoost's unique integrated exhaust manifold/cylinder head design causes head gasket stress. Coolant loss without visible leaks is a known issue on higher-mileage Focus Mk3 examples.

Severity

Severe

DIY Difficulty

Hard

Est. Cost

£500–£900

OBD Codes

P0128P0217

Component Diagram

Cooling

Typical layout and location for the Cooling assembly.

Reference Illustration

Symptoms

Coolant level drops without visible external leak
Sweet smell from engine bay
White smoke on cold starts
Overheating warning on longer journeys
Heater temperature inconsistent

Root Cause

Heat from the integral exhaust manifold repeatedly stresses the head gasket. The gasket can fail between the water jacket and combustion chamber. Some engines also have casting defects in the coolant jacket.

How To Fix

Block test for combustion gases in coolant (test kit £10 — turns yellow to green)
Head gasket replacement required if positive
Pressure test system first to rule out external leaks
Use updated MLS head gasket on reassembly
Cost: £500-900 at indie

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

2011-201540,000–100,000 miles£600–£1200

The Focus Mk3 1.0 EcoBoost shares the same timing chain vulnerability as the Fiesta Mk7. Pre-2016 engines are the highest risk — chain rattle on cold start must be investigated immediately.

Turbocharger Boost Leak from Intercooler Pipe

Moderate

2011-201850,000–120,000 miles£30–£150

Boost pressure leaks from the plastic intercooler pipes and clamp connections on the 1.0 EcoBoost are common. A leak causes a noticeable flat spot and loss of performance under boost.

Water Pump Failure (Belt-Driven Internal)

Severe

2011-201880,000–140,000 miles£250–£500

The 1.0 EcoBoost uses a belt-driven water pump. When the pump fails, coolant circulation stops and the engine overheats rapidly. Because it is inside the engine, early detection requires vigilance.

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