Subaru EJ25 Head Gasket: How to Check a Used Forester or Outback

If you are shopping a Subaru with the 2.5-liter EJ25, especially a 2001-2009 Forester or Outback, assume the head gaskets are either already replaced or on the list, and make the seller prove which. Consumer Reports, as summarized by TorqueNews, flagged 2001-2009 Forester and Outback, 2006-2008 Impreza and the 2006 Baja as the models most likely to need head gaskets, typically somewhere between 90,000 and 150,000 miles. There is no recall to fall back on, and a CarBuzz roundup put a professional gasket job at up to about $3,500.

We pulled this together on November 8, 2026, from trade coverage, a technician-facing article and a used-car dealer's own trade-in data. The short version: these cars can run a long time, and plenty of them have. But a fresh head gasket job with receipts is worth real money on an EJ25, and a vague "it's been fine" is not.

Why the EJ25 eats head gaskets

Subaru's boxer engine lies flat, so when you shut it off, oil and coolant sit against the head gasket instead of draining away. Underhood Service, a trade magazine for repair shops, explains that early EJ25s used a thick composite gasket and later ones used multi-layer steel gaskets whose coatings could still tear or corrode. The block and heads are aluminum and flex as they heat and cool, which can scrub away gasket material over time.

Underhood Service says most EJ failures show up around the 100,000-mile mark and start as a slow oil or coolant leak, and that one repair database it checked showed 484 head gasket repairs on 2003 Outbacks with the 2.5 alone. CarBuzz notes that the first- and second-generation Forester used a single-layer gasket with a graphite coating, and that complaints still show up on the 2010 model, with owners reporting about $2,920 for the repair at an average of 97,450 miles on CarComplaints.

Which years to worry about most

• 2001-2009 Forester and Outback with the non-turbo 2.5: the core of the problem, per Consumer Reports via TorqueNews.
• 2006-2008 Impreza and the 2006 Baja: also on CR's list.
• 2010-2011 EJ25 cars: fewer complaints, but CarBuzz found some.
• Later FB and FA engines: CarBuzz says Subaru moved the Forester fully to FB and FA engines by the fourth generation, with multi-layer steel gaskets and added sealant. The early fourth-gen problem was oil consumption instead, which is a different headache.

Steven Lang, who tracks long-term quality through the trade-ins he sees, wrote in The Drive that third-generation Outbacks (2003-2009) showed an 18 to 23 percent defect rate, mostly from head gaskets that went after the warranty was long gone. His advice for any Subaru eight years or older was to ask whether the gaskets were done and, if not, get it inspected independently. We agree with him, and we would add: get the answer in writing.

Turbo cars get their own warning. Underhood Service says detonation and pre-ignition can also take out EJ25 head gaskets, that it is more common on turbocharged engines because of higher cylinder pressure, and that owners who turn up the boost make it worse. So on a WRX, an STI or a Forester XT, ask directly about tunes and modifications, and be more suspicious of a quick sale than you would be on a stock Outback.

What to check before you hand over money

Start under the car with a flashlight. Since Underhood Service says these failures usually begin as a slow oil or coolant leak, look for fresh wetness or crusty coolant residue around the engine, especially along the sides where the cylinder heads sit. Then pull the dipstick and look for a white, milky substance, which TorqueNews lists as a warning sign. Check the coolant level cold, and watch the temperature gauge on a long test drive, including some idling.

• Ask for the repair invoice if the seller says the gaskets were done. A shop name, date, mileage and the parts list matter more than a verbal promise.
• Ask what coolant has been used. Subaru issued TSB 09-47-07 in October 2007 about coolant corrosion, and Underhood Service says Subaru recommends its own coolant and advises against flush machines that may have been used on other brands.
• Pay for a combustion gas test on the coolant. Our post on the head gasket chemical test explains how it works and what a positive result means.
• Price the car as if you will need the job unless you see proof it was done. If a seller will not move, that is useful information too.

What the paperwork can and cannot show

Subaru's coverage for head gasket failure is limited to its regular warranty, which Underhood Service describes as 3 years or 36,000 miles basic and 5 years or 60,000 miles powertrain. Every EJ25 Subaru on the used market today is far outside that, so this is your money, not Subaru's.

A history report sometimes shows a head gasket job when a shop reported it, and often does not. Our post on whether CARFAX shows head gasket repairs goes into why. Regular service entries still help, because frequent coolant service and oil changes are what TorqueNews says can stretch gasket life. For model-specific checks, see our used Forester guide and used Outback guide.

On cost: CARFAX's retail price for one report is usually quoted between $39.99 and $44.99. CarVins is a licensed CARFAX and AutoCheck reseller, not affiliated with CARFAX, AutoCheck or Experian, and we have been charging about $5.50 for guests, $4.50 for members and $6.75 for both reports. Confirm at checkout, since prices change. And skip the seller-supplied PDF; on a car with a known weak spot, run your own.

Sources

• TorqueNews: the Subaru models most likely to need head gaskets, per Consumer Reports
• Underhood Service: Subaru EJ25 head gasket problems
• CarBuzz: the used Subaru that will not blow a head gasket
• The Drive: Steven Lang on Subaru long-term quality