TECHNICAL SERVICE BULLETIN: SERVICE ACTION: THETA III 2.5 GDI ECM SW LOGIC IMPROVEMENT (SA642) - This bulletin provides information to upgrade the Engine Control Module ‘ECM’ system software on certain 2026MY K5 (DL3) vehicles produced from December 03, 2025 through March 09, 2026 equipped with 2.5 GDI Theta III engines. The affected vehicles may exhibit an intermittent “low oil level” message illuminated on the instrument cluster. This issue may be present due to improper calibration logic of the oil level sensor value to detect a low oil level, even if the engine oil level is within the recommended factory specification.
full bulletin at NHTSA ↗2026 Kia K5 engine problems
moderate 3 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
3
Recalls
0
Avg fix
$3,100
What stands out
Of the 5 model years of Kia K5 we track for engine problems, this one has the fewest owner complaints on file (3).
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering engine on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
TECHNICAL SERVICE BULLETIN: DATA COLLECTION: EXTRACT CALIFORNIA EMISSIONS DATA FROM ECU (DC26) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area. This bulletin provides information related to extracting “in use monitoring performance tracking” emissions data from the Engine Control Unit (ECU) of certain vehicles sold in California. The California Air Resources Board (CARB) requires the emissions data from vehicles with a minimum of 3,000 accumulated miles without reprogramming or resetting.
full bulletin at NHTSA ↗TECHNICAL SERVICE BULLETIN: DATA COLLECTION: EXTRACT CALIFORNIA EMISSIONS DATA FROM ECU (DC26) - This bulletin provides information related to extracting “in use monitoring performance tracking” emissions data from the Engine Control Unit (ECU) of certain vehicles sold in California. The California Air Resources Board (CARB) requires the emissions data from vehicles with a minimum of 3,000 accumulated miles without reprogramming or resetting.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
What owners are reporting 3 most recent
The contact owns a 2026 Kia K5. The contact stated that while driving at an undisclosed speed, the check engine warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed with an engine harness failure. The contact was informed that the engine harness needed to be replaced. The vehicle was not repaired. The contact was informed that the parts were ordered and would be…
The contact owns a 2026 Kia K5. The contact stated that after starting the vehicle, the engine immediately started to rev extremely high, and smoke was coming from under the hood, and the front passenger side lights failed to illuminate. There was a sizzling sound coming from the engine compartment, and the hood was very hot to the touch. The contact turned off the vehicle, and a tow truck…
Low oil engine warning. Oil level is okay. Car has 80 miles on it, total.
Had engine trouble with your 2026 Kia K5?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the engine problem on the 2026 Kia K5?
It's a documented issue but not catastrophic. 3 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Mileage data is limited for this issue. Owners report failures across a wide range, suggesting cause is more about driving conditions and maintenance than mileage alone.
What does it cost to fix?
Independent shops typically charge around $3,100 for engine repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to engine?
No active recalls currently cover engine issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2026/Kia/K5.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.