2015–2019 Hyundai Sonata: Engine knocking, stalling or failure (2.4L Theta II)
Likely causes, ranked
- Connecting rod bearing wearShop
Real-owner fix counts will appear here as reports come in.
DIY or shop: See DIY or shop section
Parts to check
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Symptom: A knocking noise that rises with engine speed, a flashing check-engine light with code P1326, reduced power (limp mode), or stalling.
Likely causes
- Rod bearing wear. Hyundai's warranty documents tie engine damage on these engines to connecting rod bearing wear. The knock sensor software (KSDS) watches for it and puts the car in limp mode with P1326.
DIY or shop?
Dealer. Engine work should go through Hyundai's extended coverage.
Useful steps
- Ask a Hyundai dealer if the KSDS software is installed on your VIN.
- If you hear knocking or see P1326, stop driving and have it towed.
- Keep oil change records.
Vehicle focus: 2015–2019 Hyundai Sonata.
Safety / mechanic note
A failing engine can stall in traffic or, in some cases, catch fire. Verify with a mechanic or dealer.
Related trouble codes
- P1326
Recalls & service bulletins
Technical service bulletins
- 19-01-005H-1 Hyundai extended engine long block coverage to 10 years/120,000 miles on certain 2.4L and 2.0T engines, including Sonata, once the knock sensor software is installed. Details
- TXXI Lifetime long block coverage for certain Theta II engines damaged by rod bearing wear, for original and later owners, once qualifications such as the knock sensor software are met. Details
NHTSA complaints: 879 keyword-matched complaints for Hyundai SONATA 2015–2019 (of 3,167 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-15).
Always check your VIN for open recalls at nhtsa.gov/recalls.
Sources
What actually fixed it?
Had this problem? Tell other owners what the real fix was. Reports are counted above; we never show made-up numbers.