1.0 EcoBoost vs Mitsubishi PHEV: which engine is more reliable?

According to our risk index, the Mitsubishi PHEV carries less risk than the 1.0 EcoBoost: 24/100 (low risk) versus 71/100 (high risk). The 1.0 EcoBoost has 3 documented serious faults, the main one being «Degradation of the timing belt running in oil»; the Mitsubishi PHEV has 2 documented serious faults, the main one being «Corroded air flow sensor: the petrol engine does not start to charge the battery».

Risk index

1.0 EcoBoost

High risk · 3 serious faults

Risk index

Mitsubishi PHEV

Low risk · 2 serious faults

Lower risk

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

Reviewed on 8 October 202620 sources How we work

Is the 1.0 EcoBoost reliable?

It is a turbocharged direct-injection three-cylinder that has won Engine of the Year several times, but it has two very well-documented weak points: two belts running in oil (timing and oil pump) that can disintegrate and seize the engine, and cases of coolant leaks and overheating in early units. It is best bought with a service history and the belts checked or replaced on time.^[1][2][3][4]

See the 4 of the 1.0 EcoBoost faults

Is the Mitsubishi PHEV reliable?

Yes, with caveats: the OCU ranks the Outlander PHEV first for reliability among used plug-in hybrids. What is documented are isolated campaigns (spark plugs and software, air flow sensor, fuel hose) and a possible loss of battery capacity, cited by one source and one study without figures. The Eclipse Cross PHEV, which uses the same system, has no documented faults of its own.^{[5][6][7][8][9]}

See the 5 of the Mitsubishi PHEV faults

Side-by-side comparison

Comparison of 1.0 EcoBoost and Mitsubishi PHEV
Item	1.0 EcoBoost	Mitsubishi PHEV
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	999 cm³	—
Timing	Wet belt (belt-in-oil)	Chain
Power	100–155 hp	163–224 hp
Production	since 2012^{[1][10][11][12]}	since 2013^[13][14][15]
Reliability
Risk index (what is it?)	71High risk	24Low risk
Documented faults	4	5
Of high or critical severity	3	2
Worst severity	Critical severity	High severity
Main faults	Critical severity: Degradation of the timing belt running in oil Critical severity: Oil pump belt and tensioner failure Critical severity: Coolant leaks and overheating from the turbo hose	Medium severity: Loss of traction battery (high-voltage) capacity Medium severity: Spark plugs and petrol engine software on the Outlander PHEV (campaign R3033111) High severity: Corroded air flow sensor: the petrol engine does not start to charge the battery
Most expensive documented repair	up to €1,200Degradation of the timing belt running in oilPublished figure^[2]	No reliable data
Which versions to buy
BuyRecommended versions	None	2.4 Eclipse Cross PHEV (4B12, 13.8 kWh battery, 2021-2024)^[8][9]
With cautionVersions to be cautious about	1.0 EcoBoost 100/125 (Fox, 2012-2017)^[2][3][16] 1.0 EcoBoost 100/125/140 with cylinder deactivation (from ~2017)^[17][18] 1.0 EcoBoost Hybrid 48V mild hybrid (125/155 hp, from 2019)^[1][19]	2.0 Outlander PHEV (4B11, 12 kWh battery, 2013-2018)^[7][8][20] 2.4 Outlander PHEV (4B12, 13.8 kWh battery, 2018-2021)^[5][6][7]
AvoidVersions to avoid	None	None

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

1.0 EcoBoost

See the 11 models with the 1.0 EcoBoost

Mitsubishi PHEV

Other comparisons

With the 1.0 EcoBoost

With the Mitsubishi PHEV

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Sources

Every fact on this page links to its source. If you find an error, let us know.

Ford EcoBoost engineWikipedia · Other source · consulted 26 September 2026
Alerta Ford: la correa de distribución del 1.0 EcoBoost puede romper el motor y la NHTSA ya investigaMotor16 · Motoring press · consulted 26 September 2026 · in Spanish
Los Ford 1.0 EcoBoost tricilíndricos están dando problemas de correas bañadas que recuerdan al caso PureTechMotor.es · Motoring press · consulted 26 September 2026 · in Spanish
Gripa el motor por problema en el manguito se queda sin refrigeranteOpinautos · Owners' forum · consulted 26 September 2026 · in Spanish
Mitsubishi Outlander PHEV, el híbrido enchufable de segunda mano más fiable según la OCUHíbridos y Eléctricos · Motoring press · published 14 May 2024 · consulted 8 October 2026 · in Spanish
Mitsubishi Outlander (II & III) – Bekannte Probleme und MängelGebrauchtwagenberater (Alemania) · Motoring press · published 2 March 2023 · consulted 8 October 2026 · in German
Baterías de híbrido enchufable: cuándo habrá que sustituirlas (Outlander PHEV)Autofácil · Motoring press · published 7 May 2020 · consulted 8 October 2026 · in Spanish
DVSA – base de llamadas a revisiónDVSA (Reino Unido) · Other source · consulted 8 October 2026
El Mitsubishi Eclipse Cross PHEV sí llegará a Europa, incluida España, en 2021Híbridos y Eléctricos · Motoring press · published 18 October 2020 · consulted 8 October 2026 · in Spanish
Prueba: Ford Fiesta 1.0 EcoBoost 100 CV (2013)km77 · Motoring press · consulted 26 September 2026 · in Spanish
Ford Mondeo Berlina Trend 1.0 EcoBoost 92 kW (125 CV) (2015-2018): precio y ficha técnicakm77 · Technical documentation · consulted 26 September 2026 · in Spanish
Ford B-MAX Trend 1.0 EcoBoost 100 CV (2012-2018): precio y ficha técnicakm77 · Technical documentation · consulted 26 September 2026 · in Spanish
Mitsubishi Outlander PHEVWikipedia (inglés) · Other source · consulted 8 October 2026
Mitsubishi OutlanderWikipedia (alemán) · Other source · consulted 8 October 2026 · in German
Mitsubishi 4B1 engineWikipedia (inglés) · Other source · consulted 8 October 2026
Ford EcoBoost engines: reliability, problems and should you buy one?Carbuyer · Motoring press · consulted 26 September 2026
Ford's Self-Clogging 1.0-Liter EcoBoost Engine Is Finally Getting RecalledThe Drive · Motoring press · consulted 26 September 2026
The Largest Ford EcoBoost Recalls In 15 Years Of ProductionCarBuzz · Motoring press · consulted 26 September 2026
Stellantis no es el único afectado por la correa de distribución bañada en aceiteAutofácil · Motoring press · consulted 26 September 2026 · in Spanish
Mitsubishi Outlander PHEV (2013 – 2014): alerta A12/1947/19 (sensor de caudal de aire)car-recalls.eu (alertas Safety Gate / RAPEX) · Other source · published 13 December 2019 · consulted 8 October 2026