Subaru’s EJ25 2.5L flat‑four engine is notorious for chronic head gasket failures across the 2000–2012 model years. Both Phase I and Phase II versions suffer from external coolant leaks, overheating, oil/coolant mixing, and combustion gas intrusion into the cooling system. This remains Subaru’s most infamous long‑term reliability defect.
| Year(s) | Make | Model | Should Purchase? | Notes | |
|---|---|---|---|---|---|
| 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 | Subaru | Outback | Caution |
Engine: EJ25 (Phase I & Phase II) Issues: external coolant leaks, overheating, oil/coolant mixing, combustion gas in coolant Notes: one of the most commonly affected Subaru models; failures typically occur between 80k–150k miles |
|
| 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 | Subaru | Legacy | Caution |
Engine: EJ25 (Phase I & Phase II) Issues: coolant seepage at head gasket seam, overheating, oil/coolant mixing Notes: Subaru issued coolant conditioner TSB to slow external leaks; failures still widely documented |
|
| 2000 2001 2002 2003 2004 2005 2006 2007 2008 | Subaru | Forester | Caution |
Engine: EJ25 (Phase I & Phase II) Issues: external coolant leaks, overheating, combustion gas intrusion Notes: early signs include coolant smell and bubbling in overflow tank; overheating accelerates failure |
|
| 2000 2001 2002 2003 2004 2005 2006 2007 | Subaru | Impreza (2.5L) | Caution |
Engine: EJ25 (Phase II) Issues: coolant leaks, overheating, oil seepage Notes: less common than Outback/Forester but still widely documented; Phase II gaskets prone to seepage |
|
| 2003 2004 2005 2006 | Subaru | Baja | Caution |
Engine: EJ25 (Phase II) Issues: external coolant leaks, overheating, oil/coolant mixing Notes: same EJ25 architecture as Outback; failures typically external but can progress internally |
Subaru issued multiple TSBs addressing EJ25 head gasket failures and recommended a coolant conditioner additive to slow external leaks. While no major nationwide class action was certified, head gasket failures remain one of the most documented Subaru defects, with extended goodwill repairs offered in some cases.