Mitsubishi 4B12 engine: known problems

Used in 2 guides · 2360cc · 5 known problems

Displacement

2360cc

Known problems5

Everything our guides list for the variants with this engine: the engine itself plus the gearbox and ancillaries it's paired with. Each shows which cars it's listed for.

High

CVT wear and shudder

Shares the INVECS-III CVT with the 2.0 and the same failure modes - shudder, jerkiness and eventual slipping, accelerated by the heavier engine and skipped fluid changes.

Fix: Correct Mitsubishi CVT fluid changed ~60,000km; test-drive from cold; replace/rebuild on a slipping unit.

From 100k-150k km · ~$3000-7000

Listed for: Mitsubishi ASX XA-XD

Medium

Engine oil consumption at higher km

Like the 4B11, the 4B12 can begin consuming oil as rings and valve seals age.

Fix: Monitor level, top up, and address rings/seals if consumption is heavy.

From 120k+ km · ~$200-3500

Listed for: Mitsubishi ASX XA-XD

Medium

Drive-battery degradation / reduced EV range

Like all PHEVs the 13.8kWh lithium battery loses capacity with age and cycles, cutting the usable EV range below the ~55km claim; heat, frequent rapid charging and constant 100% charging accelerate it. A full pack replacement out of warranty is very expensive.

Fix: Check state-of-health / EV range on a test drive; confirm the high-voltage battery warranty (typically 8 years/160,000km) is still valid; prefer cars charged to ~80% daily.

From 100k+ km or 6+ years · ~$0 (warranty) to $10,000+ (pack)

Listed for: Mitsubishi Eclipse Cross GK / GL

Medium

On-board charger / charging system faults

PHEV-specific charging electronics (on-board charger, DC-DC converter, charge port) can fail, leaving the car unable to charge from mains or throwing high-voltage system warnings.

Fix: Test both AC home charging and any DC charging before purchase; have HV faults diagnosed by a Mitsubishi EV-trained workshop; replace the affected module under warranty where possible.

Any · ~$1500-5000

Listed for: Mitsubishi Eclipse Cross GK / GL

Low

Petrol engine under-use fouling / fuel ageing

Owners who drive almost entirely on electricity can let the 2.4 petrol sit unused for long periods, leading to stale fuel, condensation, and the system periodically force-running the engine to burn off fuel and exercise it.

Fix: Run the petrol engine regularly and keep fresh fuel; let the car complete its engine-maintenance cycles; not a defect but a PHEV usage habit.

Any · ~$0-800

Listed for: Mitsubishi Eclipse Cross GK / GL

Cars with the 4B122

Mitsubishi ASX XA-XD

2010-2026 · 2.4L 4B12 petrol

Value

Mitsubishi Eclipse Cross GK / GL

2017-2026 · 2.4L PHEV plug-in hybrid (4B12 + twin motors)

From the FlamingCars guides for these cars. Specs are shown only where the guides agree and the value is verified.