2021 Hyundai Tucson
2021 Hyundai Tucson: Engine knock and oil consumption on the 2.4-liter GDI
The Theta II direct-injection family has a documented history of connecting rod bearing wear presenting as a knock, preceded by rising oil consumption.
- Problem
- Engine knock and oil consumption on the 2.4-liter GDI on the 2021 Hyundai Tucson
- Severity
- CriticalStop driving and address now
- Can you drive?
- Do not drive
- Typical repair
- $0–$7,500
- Usually reported at
- 70,000–140,000 miles
What is different on the 2021 Hyundai Tucson
The vehicle-specific detail — not the generic version of this fault.
The G4KJ 2.4-liter in SEL and higher trims is part of the Theta II GDI family. Across that family, Hyundai and Kia conducted multiple recalls and extended warranty programs after machining debris and oil supply issues around the crankshaft led to connecting rod bearing wear, knocking, and in some cases engine seizure. Hyundai also deployed a knock sensor detection system update on many affected vehicles that monitors for the early vibration signature and puts the car into a reduced-power limp mode before the engine fails outright.
The warning sequence owners describe is consistent. Oil consumption rises first — a quart every 1,500 to 2,000 miles where the car previously used none. Then a light metallic knock appears at idle when the engine is warm, most audible with the hood up and the car in park. Then the knock becomes audible under load. By the time the oil pressure light comes on, the bearing damage is done.
- Run the VIN through NHTSA and a Hyundai dealer before anything else. Engine recall and extended-coverage applicability is determined by VIN, and Hyundai has replaced a very large number of these engines at no cost to owners.
- Document oil consumption with dated receipts if you intend to make a claim. Hyundai's process typically requires a measured consumption test performed by a dealer.
- Out-of-coverage engine replacement: $4,500–$7,500 for a remanufactured long block installed. On a vehicle of this value, that is frequently more than the car is worth.
- The 2.0-liter G4NA in SE and Value trims is a port-injected engine and is not part of this history. If you are shopping used and want to sidestep the question entirely, buy the 2.0.
Parts involved
What a shop will be inspecting or replacing on this job.
- Connecting rod bearings
- Crankshaft
- Engine oil supply passages
- Knock sensor and engine control software
The fix and what it costs
Verify recall and extended warranty coverage by VIN immediately. If coverage applies, a dealer performs a knock sensor detection update and, where consumption or knock is confirmed, an engine replacement at no cost.
- Typical repair cost
- $0–$7,500
- Usually reported at
- 70,000–140,000 miles
Cost figures are national US estimates for planning purposes. Actual pricing varies with your vehicle, engine, location, shop labor rate, and whether OEM or aftermarket parts are used. Always get a written quote before authorizing work.
Other issues reported on the 2021 Hyundai Tucson
- Brake pulsation, usually from a dragging rear caliperThe Tucson's rear brakes are lightly loaded and seize readily in salt-belt states, producing a pulse felt in the seat rather than the wheel.
- Air conditioning weakening over a seasonThe condenser sits low and exposed behind an open lower grille, and a gradual refrigerant leak is the most common cause of poor cooling on this car.
- Clicking or no response when you turn the keyA modestly sized battery, a telematics module that stays awake, and a starter that is a known wear item on this engine family.
- Clicking from the front end on slow tight turnsA torn CV axle boot lets grease escape and grit in, and the front-wheel-drive Tucson wears out its longer passenger-side axle first.