Certain Santa Fe (TMA), Santa Fe Sport (AN), Sonata (LFA), and Tucson (TL) vehicles equipped with Theta II engines may exhibit elevated engine-out emissions. This bulletin provides instructions for updating the Engine Control Module (ECM) to address this condition.
full bulletin at NHTSA ↗2016 Hyundai Sonata engine problems
moderate 339 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Failure mileage
Complaints
339
Recalls
0
Avg fix
$3,100
11fires
When does it fail?
Of the 339 engine complaints filed for the 2016 Hyundai Sonata, here's the actual mileage breakdown — failures cluster heaviest at 0-25,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Engine accounts for 48% of every owner complaint on file for this vehicle — the dominant problem area across 12 categories tracked.
Owners have filed 339 engine complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
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.
Certain Santa Fe (TMA), Santa Fe Sport (AN), Sonata (LFA), and Tucson (TL) vehicles equipped with Theta II engines may exhibit elevated engine-out emissions. The California Air Resources Board has determined that these vehicles may be releasing air pollutants which exceed Federal and California standards.
full bulletin at NHTSA ↗Following completion of Service Campaign 9C2 (Theta II Emissions Improvement), certain vehicles may exhibit a brief hesitation or rough shifting condition during cold start operation. If present, this condition is expected to occur only within approximately the first 1-3 minutes after engine start, while the catalyst is reaching its normal operating temperature.
full bulletin at NHTSA ↗Following completion of Service Campaign 9C2 (Theta II Emissions Improvement), certain vehicles may exhibit a brief hesitation or rough shifting condition during cold start operation. If present, this condition is expected to occur only within approximately the first 1-3 minutes after engine start, while the catalyst is reaching its normal operating temperature.
full bulletin at NHTSA ↗Some vehicles may exhibit difficulty starting in cold weather. This bulletin provides the procedure to perform an inspection on the starter magnetic switch for potential freezing and, if necessary, replace the starter magnetic switch (solenoid) assembly.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2016 Sonata's most consistent problem is severe internal engine oil consumption. Owners routinely report burning 1–5 quarts per 1,000 miles with no external leaks; the oil simply disappears inside the engine. No warning lights appear until the engine is critically low or has already failed. Dealerships sometimes claim this is normal, but owners find themselves topping off oil weekly and eventually forced onto Hyundai's three-step oil consumption test (1,000-mile intervals), combustion chamber cleaning, and spark plug replacement—none of which fix the problem.
The oil loss leads directly to catastrophic engine failure. Owners describe sudden loud knocking, complete loss of power on highways at speed, or engines that simply stop and won't restart. The knock sensor recall (Campaign 953) was issued to detect these failures, not prevent them, yet Hyundai uses its completion as a gatekeep for warranty coverage—denying claims if the recall wasn't done before failure occurred.
Engine replacement is the only fix, but Hyundai denies most claims citing time in service, mileage past 5 years/60,000 miles (despite a 10-year/100,000-mile powertrain warranty promised at purchase), or piston ring failure rather than rod bearing failure. Owners report wait times of 60+ days for approval, no loaner vehicles, and case managers who are unreachable or provide conflicting denials. Multiple owners cite Hyundai's own brochure promising "lifetime warranty" or "engines for life" but found the company interpreted those terms narrowly or refused to honor them.
Same Hyundai Sonata engine reports on nearby years: 2013 · 2014 · 2015 · 2017 · 2018
Failure modes owners describe
Excessive oil consumption (internal burning)
Engine burns oil internally without external leaks, consuming 1–5+ quarts per 1,000 miles. Owners report low or no oil on the dipstick despite no visible leaks under the car. No warning lights typically appear until oil level becomes critically low or engine fails. Diagnostic tests often inconclusive; dealerships sometimes claim consumption is normal or deny warranty claims. Many owners forced to add oil weekly or even between short drives.
When: Most complaints report onset at 40,000–120,000 miles; some began after warranty expired (5 yr/60k mi standard, 10 yr/100k mi powertrain). Several owners report problem emerging within weeks of purchase.
Symptoms owners cite: Low oil level on dipstick despite no external leaks; Oil light flashing or illuminating intermittently; Engine running rough or misfiring; Fouled spark plugs saturated with oil; Strong gas smell; Rough idle or shaking at stops
Codes mentioned: P1326 (Knock Sensor Detection System), P0010, P0011 (Camshaft position timing), Misfires (no specific code cited universally)
Repairs/costs cited: Hyundai typically requires multi-step oil consumption test (3 passes of 1,000 miles each); dealership combustion chamber cleaning ($400–$800); spark plug replacement ($200+); PCV replacement mentioned. Final remedy: engine replacement ($7,000–$10,000 new engine, 12 mo/12k mi warranty on replacement). Many owners forced to pay out-of-pocket before warranty denial.
Recalls/TSBs owners mention: Extended warranty covering rod bearing failure at 150,000 miles mentioned but frequently denied if knock sensor recall (Campaign 953) not completed prior to failure. Hyundai denies claims citing 'normal consumption,' 'out of warranty by time/mileage,' piston ring failure (not rod bearing), or owner negligence. Some case managers promise engine replacement if oil combustion test fails, but follow-up denials cited. Hyundai corporate often unreachable or non-responsive.
Engine seizure and catastrophic failure
Engine abruptly seizes, locks up, or completely fails while driving with no advance warning—often while accelerating or on highway. Owners report loud ticking/knocking noise immediately before or engine suddenly stops operating entirely. Engine may not restart; requires towing and engine replacement. Seizure typically attributed to loss of oil pressure, bearing failure, or internal damage after sustained oil consumption.
When: Reported at 75,000–161,000 miles. Several occur shortly after recall service or oil consumption test procedure. Two cases report failure within 1 month of vehicle purchase; another within 6 months.
Symptoms owners cite: Sudden loud ticking, knocking, or rattling noise; Engine loss of power on highway or during acceleration; Engine cuts off and will not restart; Engine enters limp mode or reduced power mode briefly before total failure; Smoke from engine; No warning lights prior to failure (or only check engine light at moment of stall)
Codes mentioned: P1326 (Knock Sensor Detection System), Engine code (specific codes not always cited)
Repairs/costs cited: Engine replacement mandatory ($7,000–$10,000+). Some owners report new/used engines installed. Diagnosis usually confirms connecting rod bearing failure, blown pistons, loss of compression, or seized internals. Dealership wait times: weeks to months for parts and labor.
Recalls/TSBs owners mention: Theta II engines covered under lifetime warranty for rod bearing failure in some instances, but Hyundai frequently denies citing: (1) knock sensor recall (Campaign 953) not completed prior to failure—even though recall update is designed only to detect bearing failure, not prevent it; (2) vehicle out of warranty by age/mileage despite 10 yr/100k mi powertrain warranty on original owners; (3) owner negligence or 'normal wear'; (4) used vehicle purchase without full CPO status despite dealer misrepresentation. Case manager promises often overridden by corporate denial. Extended warranty (150k mi) cited but enforcement inconsistent.
Engine knock/bearing wear and reduced power incidents
Engine produces audible knocking or ticking noise during operation or cold starts. Vehicle experiences sudden loss of power, reduced-power 'limp' mode activation, or failure to accelerate beyond 30 mph while driving. Check engine light illuminates with P1326 (Knock Sensor Detection) or related codes. Symptoms consistent with early or advanced bearing wear and internal engine degradation.
When: Knock onset reported at 76,000–90,000 miles; some within weeks of knock sensor recall installation. Reduced power incidents occur on highways and city streets.
Symptoms owners cite: Audible knocking or ticking from engine (cold start or under load); Loss of power while accelerating; Reduced-power mode activation ('limp mode'); Check engine light (P1326 or P1366); Vehicle cannot exceed 30 mph; Engine runs rough or 'misses'
Codes mentioned: P1326 (Knock Sensor Detection System), P1366 (Knock Sensor related), Misfire codes
Repairs/costs cited: Knock sensor update/replacement performed under recall (Campaign 953). Some repairs attempted: engine cover replacement ($640), spark plug replacement, ignition coil replacement. No permanent fix noted in narratives; knock and power loss recur. Engine replacement ultimately required.
Recalls/TSBs owners mention: Campaign 953 (knock sensor detection software) issued; update designed to detect knock and activate warning light / reduced power mode—not to fix underlying bearing defect. Hyundai initially stated warranty covers knock-related issues, but later told owners warranty only covers 'complete engine failure,' not early knock symptoms. Owners cite warranty brochure promising lifetime coverage for engine repairs related to defect, but corporate denies based on time in service or mileage thresholds.
Stalling and loss of power on highways/in traffic
Engine suddenly stalls or loses power while driving, particularly on highways at speed, with no prior warning lights or symptoms. Vehicle may restart after cooling or not restart at all. Creates dangerous situation: drivers stranded in traffic lanes or on freeways, nearly hit by other vehicles, unable to move car to safety. Some cases involve multiple stall events over months; others single catastrophic event.
When: Reported across wide mileage range (32k–135k+ miles). Multiple incidents within same vehicle over weeks to months.
Symptoms owners cite: Engine suddenly stops or loses power (no restart or restart after delay); No warning lights prior to stall; Stall occurs at highway speed (60+ mph) or during normal driving; Engine tries to turn over but dies ('slowly dies out'); Multiple stalls in same vehicle over time
Codes mentioned: P1326 (in some cases), Battery/electrical codes (misdiagnosed in some instances)
Repairs/costs cited: No consistent repair found in narratives. Dealerships have misdiagnosed as dead battery, faulty starter, electrical issue, or battery replacement needed ($275+). Ultimately, engine replacement or internal inspection reveals oil starvation, bearing failure, or internal damage.
Recalls/TSBs owners mention: No substantive response cited. Dealerships claim engine 'passed' diagnostic or refuse to investigate. Hyundai corporate unreachable or non-responsive when contacted by owners. One case cites warranty denial due to incomplete knock sensor recall.
Valve failure and combustion chamber damage
Burned or stuck valve (hole in valve, valve stuck open), fouled/oil-saturated spark plugs, and oil intrusion into combustion chamber observed. Owners report misfire in specific cylinder, rough running, and cylinder head damage. Some attribute to excessive oil consumption leading to oil coating combustion surfaces and valve damage.
When: Reported at 75,000–100,000 miles (well within warranty period).
Symptoms owners cite: Misfire in specific cylinder (e.g., cylinder 3); Engine rough or loss of power on hills/acceleration; Oil-saturated/fouled spark plugs; Oil intrusion into combustion chamber; Valve stuck open or burned (hole in valve)
Codes mentioned: Misfire codes (e.g., cylinder 3 misfire), P1326 (in one case)
Repairs/costs cited: Cylinder head machine/repair ($3,500+), spark plug replacement, ignition coil replacement, head gasket replacement. One owner paid $3,500 out-of-pocket for valve and head gasket repair at 75k miles (within warranty). Some owners' valve repairs preceded other engine failures.
Recalls/TSBs owners mention: One case: no response; another involved warranty denial. Generally, dealerships perform repairs but Hyundai denies or delays warranty approval.
Engine failure after knock sensor recall or service appointment
Engine fails, knocks, or enters limp mode within days or weeks of knock sensor recall (Campaign 953) completion or during dealership oil consumption test procedure. One owner reports engine 'blew' while being inspected at dealership post-recall; another reports knocking discovered during recall service and car shut down 30 minutes after pickup. Pattern suggests recall procedure or underlying defect acceleration during diagnostic testing.
When: Failures occur immediately post-recall (within days) or during scheduled oil consumption tests (1,000-mile intervals).
Symptoms owners cite: Knocking noise during or immediately after recall inspection; Engine enters limp mode or fails shortly after recall completion; Engine shuts down while parked at dealership; Misfiring or stalling during oil consumption test procedure
Codes mentioned: P1326
Repairs/costs cited: Engine replacement required. Dealerships place hold on vehicle pending Hyundai corporate approval; approval often denied or delayed for weeks/months.
Recalls/TSBs owners mention: Hyundai denies engine replacement citing recall not completed prior to failure (even though failure occurs post-recall or during recall service), or claims underlying defect is piston ring failure (not rod bearing) and thus outside extended warranty scope. Dealerships receive denial from corporate within hours to days.
Warranty denial and coverage disputes
Hyundai denies warranty claims for engine failures, excessive oil consumption repairs, or knock-related issues on grounds including: (1) knock sensor recall (Campaign 953) not completed prior to failure; (2) vehicle out of warranty by time (5 yr/60k mi standard) or mileage despite 10 yr/100k mi powertrain warranty stated at purchase; (3) used vehicle purchase status; (4) owner negligence or 'normal wear'; (5) piston ring failure vs. rod bearing failure; (6) extended warranty expired or inaccessible. Many owners cite Hyundai's own brochure or website claiming 'lifetime warranty' or 'engines for life' but corporate takes narrow interpretation.
When: Denials occur at any mileage but typically when vehicle exceeds 5 yr/60k mi mark or when knock sensor recall not completed. Some denials issued after 60+ days or months of waiting.
Symptoms owners cite: Warranty claim submitted; corporate denies within days to weeks; Case manager assigned but unreachable or non-responsive; Dealership told claim denied; conflicting reasons given by different representatives; CPO status misrepresented at purchase (promised 10 yr/100k mi; later told only 5 yr/60k mi applies)
Repairs/costs cited: Owners forced to pay out-of-pocket for repairs ($400–$10,000+) or vehicle remains stranded at dealership. Some owners pursue GWC (third-party warranty) or attorney for class-action lawsuit. Reimbursement promised but rarely issued.
Recalls/TSBs owners mention: Hyundai Motor America denies claims via case managers citing policy narrow interpretations. Some owners appeal; outcomes inconsistent. Hyundai states knock sensor recall (Campaign 953) is prerequisite for bearing warranty but offers no explanation why detection update would prevent bearing failure. Extended 150k mi warranty advertised but enforcement conditions are vague or disputed.
Synthesized from 339 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 5 most recent
My car is involved in the class action lawsuit because of engine failure and fire with my 2016 Hyandia Sonota. I have concerns with the above issue because of knocking in the engine and using 1 quart of oil every 400 miles. Hyandia extended the Power train settlement for life time. Yet, they denied to do anything about my car because or 98,700 milage. Dealer said only way Hyandia will do anything…
My 2016 Hyundai Sonata experienced a sudden engine failure while in operation with no prior warning lights or symptoms. The engine seized unexpectedly, creating a safety risk. This failure appears consistent with known engine defects affecting Hyundai Sonata vehicles of this model year. Hyundai Motor America denied my claim without addressing these known defect patterns.
My 2016 Hyundai Sonata is sitting at the Red Hoagland dealership in Winter Haven, FL after the engine started knocking. Rather than continue driving it and risk an accident with our 19-yr old child driving it, or risk worse damage to the engine, I had it towed to Red Hoagland service department. This occurred less than a week after we had it at the dealership for the third and final oil…
took my car to Hyundai at Tustin to check recall car worked fine dec 14 to 15th took my car drove it 4 days started hearing a whistle noise never herd it before then a small taping noise that kicked in when ac was on then when i drove it less then 10 miles the car started to stall and the engine light started flashing then i took it to car max due to having car max toeing plan they took the car…
It burns through about 2.5 quarts of oil every oil change and Hyundai says that normal... That's far from normal.
Had engine trouble with your 2016 Hyundai Sonata?
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 2016 Hyundai Sonata?
It's a documented issue but not catastrophic. 339 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?
Across the 92 complaints that reported odometer mileage, most engine failures cluster between 59,013 and 119,345 miles, with the median around 88,000. A quarter of owners report trouble before 59,013; a quarter make it past 119,345. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
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/2016/Hyundai/Sonata.
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.