CriticalCommonEngine

Subaru WRX: EJ20/EJ257 Ringland Piston Failure

EJ20/EJ257 Ringland Piston Failure is a common engine fault on the Subaru WRX on the 1992–2011 cars, and we rate it critical. Putting it right costs $4,500 to $9,500 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 41 documented faults on the Subaru WRX.

Vehicle: Subaru WRX
Only on: STI / 2.5 turbo
Engine: EJ20 / EJ257
Years: 1992–2011
Fuel: petrol
System: Engine

This page covers the Subaru WRX 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 WRX faults41 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Turbocharger yet. We would rather show none than show a picture of a different part.

What goes wrong

The EJ20 turbo (GC8/GF8/GD/GG) and EJ257 2.5T (GH/GR STI) are both prone to ringland cracking and piston failure under detonation or sustained high boost. Pistons in these engines use a relatively thin land between the top and second ring grooves. Knock events, poor fuel quality, lean AFR, or aggressive tuning cause the land to crack or collapse, destroying the piston and scoring the bore. Extensively documented in NZ/AU where 98RON fuel use and JDM tune mismatches are common.

What you would notice

Sudden loss of power with loud knocking or ticking
Blue or grey smoke from exhaust under acceleration
Engine misfire on one cylinder
Compression test showing one low cylinder
Oil consumption increasing rapidly

How to check it

Where to look. Pistons in all four cylinders of the horizontally-opposed engine; bore and rings also affected once ringland collapses

Check for evidence of tuning (aftermarket ECU, pod filter, intercooler).
Ask about fuel used - 91RON is a known ringland killer on EJ20T/EJ257.
Inspect boost controller and check if factory boost levels have been raised.
Listen for any knock under hard acceleration.
If a workshop inspection is possible: Perform a cylinder compression and leak-down test.

Parts involved: Turbocharger.

What it costs to put right

$4,500 to $9,500 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 engine ever been tuned or had the boost raised?”
“What fuel grade has been used consistently?”
“Has a compression or leak-down test been done?”
“Is there any history of engine knock or misfire?”

Now check the Subaru WRX 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 WRX buyer questions

Is ej20/ej257 ringland piston failure serious on a Subaru WRX?

We rate it critical and common on the Subaru WRX. The EJ20 turbo (GC8/GF8/GD/GG) and EJ257 2.5T (GH/GR STI) are both prone to ringland cracking and piston failure under detonation or sustained high boost. Pistons in these engines use a relatively thin land between the top and second ring grooves. Knock events, poor fuel quality, lean AFR, or aggressive tuning cause the land to crack or collapse, destroying the piston and scoring the bore. Extensively documented in NZ/AU where 98RON fuel use and JDM tune mismatches are common.

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

$4,500 to $9,500 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 WRX years are affected?

Our research records this fault on the 1992–2011 Subaru WRX. 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 for evidence of tuning (aftermarket ECU, pod filter, intercooler). Ask about fuel used - 91RON is a known ringland killer on EJ20T/EJ257. Inspect boost controller and check if factory boost levels have been raised. Listen for any knock under hard acceleration. If a workshop inspection is possible: Perform a cylinder compression and leak-down test. Look here: Pistons in all four cylinders of the horizontally-opposed engine; bore and rings also affected once ringland collapses