Subaru Impreza
World's first boxer diesel — technically fascinating, acoustically disappointing. No boxer rumble like the petrol: sounds like a regular diesel with shifting ECU injection noises that vary day to day. Crankshaft failure on 2008-2010 from stress risers in the aluminum block next to steel inserts — Subaru revised the crankshaft three times (12200AA380→AA381→AA480) without ever issuing a recall. DPF clogs on short trips, oil dilution from post-injection during active regen — ECU only estimates dilution, doesn't measure it. 2012+ (XV/Forester SJ) largely free of crank issues. 2015+ (Euro 6) almost trouble-free. Liqui Moly diesel additive lowers regen temperature per community. Timing belt every 100k km mandatory.
Diesel Impreza hatch — same engine, same problems
Same EE20, hatchback body. Unsuitable for short trips (DPF), economical for long distance. Only buy post-2012 with service history.
Engine Weaknesses 5
Cracks at the rear main bearing journal from insufficient material strength and incorrect factory torque specs. Failure typically between 50-80k miles, often without warning. Subaru corrected both causes (sealant + torque) after 2011.
Symptoms: Sudden knocking from engine, oil pressure loss, engine seizure
Diesel particulate filter clogs with predominantly short-trip driving — regeneration doesn't initiate. Check engine light, power loss, forced dealer regeneration.
Symptoms: Check engine light, power loss, increased consumption, DPF warning light
Frequent DPF regeneration injects diesel into the oil — oil level rises, viscosity drops. Accelerated wear if not changed in time.
Symptoms: Oil level above max, diesel smell on dipstick, thin oil
HPFP failure causes cold start difficulties and misfires. Expensive part due to boxer installation position.
Symptoms: Cold start difficulties, misfires, check engine light
Glow plugs fail, especially on older examples. Poor cold start, increased emissions.
Symptoms: Poor cold start, white smoke on startup, glow plug warning light
Vehicle Weaknesses 4
Recall WUE-90 (2008–2017): silicone-based household spray residue on switch contacts prevents brake lights from illuminating. CVT vehicles cannot be shifted out of Park.
Synchro rings in the manual gearbox wear at higher mileage — 2nd and 3rd gear become notchy or crunch when shifting.
Typical Subaru wear item for this generation. Rear wheel bearings fail earlier than expected due to corrosion in salt regions.
Impreza GE is considered underbrakered for its drivetrain — brake pads need replacing unusually early. Front axle most affected.