MajorCommonBody & Rust

Subaru STI: Rear Wheel Arch and Sill Rust (JDM Imports)

Rear Wheel Arch and Sill Rust (JDM Imports) is a common body & rust fault on the Subaru STI on the 1992–2021 cars, and we rate it major. Putting it right costs $800 to $4,500 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 32 documented faults on the Subaru STI.

Vehicle: Subaru STI
Years: 1992–2021
Fuel: petrol
System: Body & Rust

This page covers the Subaru STI 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 STI faults32 documented faults on this model

What you are looking at

No photograph available

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

What goes wrong

Japanese domestic market WRX imports entering NZ from the 1990s onwards are susceptible to rust in the rear wheel arches, inner sills, and floor pan due to NZ's wetter climate relative to Japan's drier regions. Factory underseal is thin and cracks with age, allowing salt and moisture ingress. The rear inner arch seams and the sill drain channels are the primary rust initiation points. Structural sill rust is a WoF failure and can compromise body rigidity.

What you would notice

Bubbling paint on rear wheel arches
Rust visible at bottom of door sills
Soft or spongy floor pan when pressing underfoot
Musty smell inside cabin
Visible rust holes or perforation in wheel arch lips

How to check it

Where to look. Rear wheel arches (inner seams and lips), door sills, floor pan corners, and spare wheel well

Inspect rear wheel arch lips and inner seams closely - push along the inner arch seam and feel for softness indicating rust through.
Check door sill ends and lower sill edges with a screwdriver (light probing).
Look under the carpet at the floor pan corners.
Inspect the spare wheel well for standing water or rust.
If a workshop inspection is possible: Check jacking points for structural integrity.

Parts involved: Body corrosion.

What it costs to put right

$800 to $4,500 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 car ever had any rust repairs done?”
“How long has the car been in NZ and where was it kept (coastal/inland)?”
“Has the underbody ever been treated or rust-proofed?”
“Is there any bubbling paint around the wheel arches?”

Now check the Subaru STI 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 STI buyer questions

Is rear wheel arch and sill rust (jdm imports) serious on a Subaru STI?

We rate it major and common on the Subaru STI. Japanese domestic market WRX imports entering NZ from the 1990s onwards are susceptible to rust in the rear wheel arches, inner sills, and floor pan due to NZ's wetter climate relative to Japan's drier regions. Factory underseal is thin and cracks with age, allowing salt and moisture ingress. The rear inner arch seams and the sill drain channels are the primary rust initiation points. Structural sill rust is a WoF failure and can compromise body rigidity.

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

$800 to $4,500 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 STI years are affected?

Our research records this fault on the 1992–2021 Subaru STI. 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?

Inspect rear wheel arch lips and inner seams closely - push along the inner arch seam and feel for softness indicating rust through. Check door sill ends and lower sill edges with a screwdriver (light probing). Look under the carpet at the floor pan corners. Inspect the spare wheel well for standing water or rust. If a workshop inspection is possible: Check jacking points for structural integrity. Look here: Rear wheel arches (inner seams and lips), door sills, floor pan corners, and spare wheel well