Connecting rod bearing failure on the Hyundai/Kia Theta II

The 2.0 and 2.4 litre Theta II knocks, then seizes, and in some cases catches fire. It is the most-recalled engine in the modern American used market — four separate campaigns, a regulator finding that the recalls came too late, and a class settlement covering roughly four million cars. The single fact worth knowing before you buy: that settlement carries a lifetime warranty on the short block, with no mileage limit — but it is conditional on the knock sensor software having been installed, so check that first.

Symptoms

A metallic knocking or ticking from the bottom of the engine that rises and falls with engine speed, usually loudest at idle when warm. The oil pressure warning light may come on. Left alone it ends in a seizure — NHTSA's concern in the recalls is a stall at speed, and in the later ones a fire: "a damaged connecting rod could puncture the engine block and cause engine oil to leak" onto hot components.

Likely cause

Different in the two waves of recalls, which is why they read differently. The 2015 and 2017 campaigns are a manufacturing fault: "metal debris ... generated from factory machining operations as part of the manufacturing of the engine crankshaft" (15V-568), which restricts oil flow to the bearings and wears them out early. Kia's filing adds that "the machining processes of the crankpins caused an uneven surface roughness" (17V-224). The 2020 campaigns describe premature rod bearing wear as a fire risk without pinning it to machining. So the mechanism is oil starvation at the bearing, arrived at by more than one route.

How should it be checked?

Check the settlement before anything else, and check it in the right order — because the two halves are linked and most summaries miss the link. First: has the knock sensor software been installed? The settlement administrators' own wording is explicit that the lifetime warranty covers "those Class Vehicles owned by individual consumers who have completed the Knock Sensor Detection System Update". So the software is not an optional extra alongside the warranty — on the record as published, it is the condition for it. A car without the update may be a car without the cover. Then the warranty itself. *In re Hyundai and Kia Engine Litigation* (C.D. Cal. 8:17-cv-00838-JLS-JDE) and *Flaherty v. Hyundai* (18-cv-02223), before Judge Josephine Staton: "the Powertrain Warranties for the Class Vehicles will be extended to a Lifetime Warranty ... will cover the short block assembly, consisting of the engine block, crankshaft and bearings, connecting rods and bearings, and pistons". And it runs "for bearing wear or damage irrespective of the Class Vehicle's mileage, duration of ownership, or prior warranty engine repairs". The covered list is much wider than the recall list: 2011–2019 Sonata, 2013–2019 Santa Fe Sport, 2014–2015 and 2018–2019 Tucson, and 2011–2019 Kia Optima, 2012–2019 Sorento and 2011–2019 Sportage — all with the 2.0 or 2.4 Theta II GDI. A 2016 Optima is in no Theta recall at all and is still covered here.

How can you check it yourself?

Listen at a warm idle with the bonnet up, from the side of the engine rather than the front — the knock is low and rhythmic and speeds up with the engine. Check the dipstick for level and for metallic glitter in the oil. Then run the VIN on nhtsa.gov/recalls: an open campaign is free work waiting to be done, and a completed one tells you the engine may already have been replaced.

The question to ask the shop

Has the engine ever been replaced or the short block rebuilt under the settlement or a recall — if so, when, at what mileage, and is there paperwork? Has the knock sensor detection software been installed? Is this car on the settlement's covered list, and does the lifetime short-block warranty follow it to me?