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Subaru Legacy: EJ20/EJ25 head gasket failure

EJ20/EJ25 head gasket failure is a very common engine fault on the Subaru Legacy on the 2003–2009 cars, and we rate it critical. Putting it right costs $2,500 to $4,800 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 54 documented faults on the Subaru Legacy.

Vehicle
Subaru Legacy
Engine
EJ20 / EJ25
Years
2003–2009
Fuel
petrol
System
Engine

This page covers the Subaru Legacy as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Subaru Legacy faults54 documented faults on this model

What you are looking at

A removed multi-layer steel head gasket held up, showing staining around the cylinder bore.Example of the part — not this vehicle

A used multi-layer head gasket. Discolouration between a cylinder and a water gallery is the tell.

John Furman · CC BY-SA 3.0 · Wikimedia Commons

What goes wrong

The EJ20 and EJ25 flat-four engines fitted to BP/BL Legacy are highly prone to external coolant and oil leaks at the head gaskets, and in severe cases internal coolant consumption leading to overheating and engine damage. Subaru NZ and AU acknowledged the issue with an extended warranty programme covering some vehicles. The EJ25 2.5 non-turbo is the most frequently affected variant. Head gasket replacement requires full engine removal and cylinder head resurfacing.

What you would notice

  • Coolant loss without visible external leak
  • White or sweet-smelling exhaust smoke
  • Oil and coolant mixing visible as milky residue on dipstick or filler cap
  • Overheating in traffic or under load
  • External oil or coolant weeping at cylinder head mating surface

How to check it

Where to look. Cylinder head gaskets, both left and right sides of the EJ flat-four engine

  1. Check radiator coolant level and condition for oil contamination.

  2. Inspect both sides of the engine block at the head gasket line for oil or coolant seepage.

  3. Run a combustion leak (block) test on the coolant reservoir.

  4. Check oil filler cap and dipstick for milky emulsion.

  5. Review service history for coolant top-ups between services.

Parts involved: Head gasket.

What it costs to put right

$2,500 to $4,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the head gasket ever been replaced, and by whom?”
  • “When was the coolant last changed and what colour is it now?”
  • “Has the car ever overheated or needed coolant top-ups between services?”

Now check the Subaru Legacy you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Subaru Legacy buyer questions

Is ej20/ej25 head gasket failure serious on a Subaru Legacy?

We rate it critical and very common on the Subaru Legacy. The EJ20 and EJ25 flat-four engines fitted to BP/BL Legacy are highly prone to external coolant and oil leaks at the head gaskets, and in severe cases internal coolant consumption leading to overheating and engine damage. Subaru NZ and AU acknowledged the issue with an extended warranty programme covering some vehicles. The EJ25 2.5 non-turbo is the most frequently affected variant. Head gasket replacement requires full engine removal and cylinder head resurfacing.

How much does it cost to fix on a Subaru Legacy?

$2,500 to $4,800 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Subaru Legacy years are affected?

Our research records this fault on the 2003–2009 Subaru Legacy. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Check radiator coolant level and condition for oil contamination. Inspect both sides of the engine block at the head gasket line for oil or coolant seepage. Run a combustion leak (block) test on the coolant reservoir. Check oil filler cap and dipstick for milky emulsion. Review service history for coolant top-ups between services. Look here: Cylinder head gaskets, both left and right sides of the EJ flat-four engine