The EJ257 is the turbocharged 2.5-liter boxer engine in the Subaru WRX STI. Its most commonly reported problems are ringland failure (cracked piston ringlands, usually after detonation), rod bearing failure, oil starvation and oil pickup problems, turbo oil feed restrictions, and head gasket leaks on some engines. With stock power and careful maintenance many run well, but added boost and poor fuel quickly expose its limits.
Common EJ257 problems
Ringland failure
Detonation from low-octane fuel, lean conditions or aggressive engine calibration can crack the ringlands, the thin piston sections between the rings. Symptoms include low compression on one cylinder, blow-by, smoke and misfires; see Subaru head gasket and ringland failure and compression test.
Rod bearing failure
Spun rod bearings are widely reported, often linked to oil starvation during hard cornering, low oil level, oil breakdown and high rpm. A knock that rises with engine speed is the warning; see spun rod bearings and engine knocking.
Oil pickup and oil control
A failed oil pickup O-ring or a low oil level lets the pump draw air, dropping oil pressure. Keep the level at the full mark and check it often on track-driven cars; see low oil pressure.
Turbo oil feed
The turbo oil feed line on many Subaru turbo engines has a fine filter screen in its banjo bolt that can clog, starving the turbo; see turbo failure symptoms.
Head gaskets
Head gasket leaks occur on EJ engines, though they are associated more with the naturally aspirated EJ25; see oil in coolant and signs of a blown head gasket.
Warning signs to act on
- A new knock or tick that rises with rpm
- Oil consumption that suddenly increases, or blue smoke
- A misfire on one cylinder that does not move with the coil
- Oil pressure that drops in hard corners or at hot idle
Stop hard driving and diagnose; catching a failing bearing early can save the block.
Is the EJ257 reliable?
At stock power, with quality fuel, frequent oil changes and the oil level kept full, many EJ257s last. Its open-deck design and cast pistons limit how much extra boost it tolerates, which is why built blocks with closed decks and forged internals are popular for higher power; see closed deck vs open deck and EJ255 vs EJ257.
Replacing a failed EJ257
Our built Subaru short blocks include the Turn In Concepts Stage 3+2 closed-deck EJ257 short block at $6,799.00, plus IAG Performance EJ25 short and long blocks; see our Subaru EJ25 engines page.
More guides: what is a boxer engine? · WRX vs STI · EJ25 problems · forged vs cast pistons · EJ257 specs · head studs vs head bolts · Subaru oil pickup tube · FA20 vs EJ25.
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.