The Subaru EJ25 is famous for one thing: blowing head gaskets. The 1999-2009 SOHC EJ253 in Outback, Forester, Legacy, and Impreza is the worst offender. Subaru extended warranty coverage in 2014 (Class Action W-001) for 8 years/100,000 miles.
High failure rate on head gaskets - the defining EJ25 problem. Subaru extended head gasket warranty to 8yr/100K. Outside head gaskets, the bottom end is durable.
SOHC EJ253 head gaskets fail externally - oil weeping down the side of the engine, sometimes coolant too. Subaru class-action W-001 (2014) extended head gasket warranty to 8yr/100K on 2002-2012 vehicles. Six-Star Subaru gasket update is the standard fix.
View P0301 Diagnosis →Early FB25 engines (Outback/Forester 2011-2014) burn oil - covered by the Yaeger v. Subaru class action settlement (2016). Mostly piston ring related. Note: this is the FB25, not classic EJ25.
View P0507 Diagnosis →EJ25 timing belt at 105K - interference engine. Skip it and you bend valves.
Subaru cats clog or break apart, often related to upstream oil burning or rich condition. Triggers P0420.
View P0420 Diagnosis →Knock sensor on top of the block fails after 100K. Throws P0328.
View P0328 Diagnosis →Standard age-related leak on both banks.
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1999-2002 EJ25 Phase II - worst head gasket rate. 2002-2005 Outback/Forester/Impreza without verified head gasket update.
2006-2009 EJ253 (better gaskets but still vulnerable). Better: 2015+ FB25 Outback/Forester (post oil-consumption fix). Skip the FB25 transition years 2011-2014.
On any 1999-2009 EJ25, budget $1,800-$3,500 for head gaskets between 100K-150K and $700-$1,400 for timing belt at 105K. Combine the two jobs.
If your EJ25 is throwing a check engine light, these are the codes most often associated with the problems above. Click any code for full diagnosis steps and typical repair costs.
The Phase II SOHC gasket material is too thin and degrades under the boxer engine's thermal cycling. External oil leaks first, sometimes coolant. The Six-Star MLS gasket update solves it permanently.
No formal recall, but Subaru extended head gasket warranty to 8 years/100,000 miles on 2002-2012 vehicles under Class Action W-001 (settled 2014). Most claim periods are now closed.
1996-2012 Legacy/Outback 2.5L, 1998-2012 Forester 2.5L (non-turbo), 1999-2011 Impreza 2.5L. The turbo EJ257 (WRX STI) is a different beast with rod bearing problems.
With timely head gasket service: 250,000+ miles. Without: usually 150K-180K before catastrophic head gasket failure.
Only if the head gaskets have been updated to MLS - or if the price reflects the upcoming $2,000-$3,500 job. Verify with receipts.
EJ25 is the older 1996-2012 boxer with head gasket problems. FB25 is the 2011+ replacement with carbon and oil consumption issues - especially 2011-2014. 2015+ FB25 is much improved.