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2 faults documented by at least two sources, listed by version then by mileage at onset when known.
2 known faults
On the 1.0 T-GDi, the clutch is the most frequently reported fault in Fiches-auto's owner reviews (small sample). CarVerif mentions a clutch that is sometimes weak, with a combined risk to the clutch, turbo and coils on the 120 hp beyond 120,000 km. These are owner reports, not manufacturer statistics.
On the 1.0 T-GDi, the clutch is the most frequently reported fault in Fiches-auto's owner reviews (small sample). CarVerif mentions a clutch that is sometimes weak, with a combined risk to the clutch, turbo and coils on the 120 hp beyond 120,000 km. These are owner reports, not manufacturer statistics.
A recall concerns the tandem pump of Kia 1.6 CRDi engines, which the Stonic was built with between 2019 and April 2020 (ÖAMTC gives 26.08.2019 to 14.04.2020; CarVerif gives 26 June 2019 to 14 April 2020). A design fault in the internal filter can, in the worst case, reduce braking assistance. The dealer removes the filter and replaces the pump and the belt if necessary. Eligibility can be checked using the serial number.
Fixed free of charge by a dealer and not counted in the reliability score: ask for proof the work was done (invoice, or a VIN check at a dealer).
No recurring fault documented for: 1.0 T-GDi 100 DCT7, 1.0 T-GDi 100 MHEV.
An OBD scanner plugged in under the steering wheel shows stored fault codes, even with warning lights off: useful during the test drive.
Compare prices of parts for the Kia Stonic I (timing, brakes, filters) to estimate the repairs to plan for.