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 ↗2017 Hyundai Sonata engine problems
moderate Owners of the 2017 Hyundai Sonata have filed 292 NHTSA complaints about the engine, typically surfacing around 82,000 miles at roughly $3,100 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See engine across all vehicles →
Failure mileage
Complaints
292
Recalls
0
Avg fix
$3,100
| Model year | engine complaints |
|---|---|
| 2013 Sonata | 545 |
| 2014 Sonata | 215 |
| 2015 Sonata | 412 |
| 2016 Sonata | 342 |
| 2017 Sonata (this page) | 292 |
| 2018 Sonata | 138 |
| 2019 Sonata | 68 |
| 2020 Sonata | 11 |
| 2021 Sonata | 19 |
2crashes
6fires
When does it fail?
Of the 292 engine complaints filed for the 2017 Hyundai Sonata, here's the actual mileage breakdown — failures cluster heaviest at 50,000-75,000 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 38% of every owner complaint on file for this vehicle — the dominant problem area across 12 categories tracked.
Owners have filed 292 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 2017 Sonata accumulates complaints of severe engine oil consumption starting as early as 60,000 miles and worsening progressively. Owners report needing to add oil every 500–1,000 miles or weekly, despite no visible leaks. This consumption fouls spark plugs and ignition coils monthly or more frequently, requiring expensive replacements. Dealership oil consumption tests confirm the excessive burn, yet corporate Hyundai denies engine replacement claims citing mileage or time limits, even when vehicles carry recall campaign updates (Campaign 953 KSDS software/knock sensor).
Simultaneously, owners describe sudden engine misfires, loss of power on highways, rough idle, and unintended limp mode activation (capping speed at 30–60 mph) without warning—creating serious safety hazards. Excessive oil burning damages catalytic converters and clogs exhaust systems. In severe cases, engines seize, lock up, or suffer catastrophic internal failure (metal shavings, bearing wear, low/zero cylinder compression), requiring complete replacement at $3,880–$12,000+.
Dealerships and Hyundai deploy lengthy multi-stage testing, combustion cleaning, and parts replacement as stall tactics. Many owners report waiting months with their vehicle stranded at dealership lots while corporate denies coverage based on technicalities—VINs outside recall scope, mileage exceeding arbitrary thresholds, previous ownership, or settlement agreement fine print. Some are offered depreciated buyback instead of repair, costing the owner thousands in lost equity.
Same Hyundai Sonata engine reports on nearby years: 2014 · 2015 · 2016 · 2018 · 2019
Failure modes owners describe
Excessive Oil Consumption / Internal Oil Burning
Engine consumes oil at rates ranging from 1 quart per 500–1000 miles to as much as 3 quarts per 230 miles. Oil consumption occurs without visible leaks under vehicle or garage floor. Suspected causes include piston ring deterioration, oil bypass into combustion chambers, or internal seal failure. Symptoms often appear between 60,000–100,000 miles and progressively worsen.
When: Typically 60,000–100,000 miles; some reports as early as first year of ownership
Symptoms owners cite: Must add oil every 1–2 weeks or every 500–1000 miles; Oil dipstick comes up bone dry despite recent oil changes; Oil warning light illuminates between scheduled services; No visible leaks or drips on driveway; Burning smell or white smoke from exhaust; Oil pooling on spark plugs requiring frequent replacement
Repairs/costs cited: Owners report dealership oil consumption tests (drive 1000 miles, recheck), combustion chamber cleaning, spark plug replacement (monthly or more), ignition coil replacement. Costs cited: $500–$700 for combustion cleaning; multiple spark plug/coil replacements. Engine replacement cost: $3,880–$12,000. Many repairs fail to resolve the issue.
Recalls/TSBs owners mention: Service Campaign 953 (KSDS software update). Extended warranty programs mentioned but frequently denied. Hyundai considers 1 quart per 1000 miles acceptable despite owner complaints of much higher consumption. Warranty extensions tied to recall campaigns; many vehicles outside recall scope denied coverage.
Engine Misfires / Loss of Power / Stalling
Engine misfires, stumbles, or stalls suddenly, often triggered by excessive oil consumption fouling spark plugs and ignition coils. Vehicle enters limp mode (reduced to 30–60 mph max), check engine light illuminates (solid or blinking), and vehicle may lose acceleration without warning.
When: Variable; tied to oil consumption onset; some reports mid-travel, others during acceleration or highway driving
Symptoms owners cite: Engine light illuminates (blinking or solid); Sudden loss of power or acceleration; Vehicle enters limp mode, maxing out at 30–60 mph; Rough idling or violent engine shaking; Check engine light accompanied by misfires; Engine stalls without warning; Cylinder-specific misfires (codes P0300-P0304 implied; P1326 reported in hybrids)
Codes mentioned: P1326, P0420, Cylinder misfires (cylinders 2, 4 noted)
Repairs/costs cited: Dealerships initially replace spark plugs and ignition coils; costs $500–$700. Oil consumption testing performed; combustion chamber cleaning attempted. If problem persists, engine replacement quoted at $3,880–$12,000. Some owners report knock sensor replacement under recall campaign 953.
Recalls/TSBs owners mention: Campaign 953 (KSDS software update and knock sensor installation/replacement). Extended warranty coverage under recall campaigns but often denied for vehicles outside mileage or time limits. Some owners report Hyundai refuses repair until engine 'completely fails.'
Oil Drain Plug Failure / Low-Quality Oil Pan Assembly
Oil drain plug falls out or loosens during or after oil service, causing rapid oil loss and severe engine damage. One owner cites difficulty identifying fused gasket in recessed oil pan due to matching color; alleges NHTSA paint-fused gasket design defect.
When: Shortly after oil service (one case: 2 miles from destination after oil change at independent shop; another case: weeks after dealership service)
Symptoms owners cite: Oil warning light and check engine light illuminate after travel; Engine stops/stalls due to oil starvation; No oil detected in engine (locked/seized condition)
Repairs/costs cited: Engine replacement: $9,342 reported for one case. Owner disputes responsibility when oil change performed by third party; dealership/manufacturer initially denied claim citing improper technician tightening.
Recalls/TSBs owners mention: NHTSA Investigation DP 22-003 (oil drain pan assemblies). One owner disputes NHTSA final conclusion blaming incorrect maintenance, citing design flaw (paint-fused gasket not easily visible in recessed pan). Hyundai warranty/manufacturer coverage contingent on service facility; owner/third-party service claims often denied.
Connecting Rod Bearing Failure / Knock Sensor Detection System (KSDS) Issues
Engine exhibits knock/pinging noise and elevated oil consumption indicating internal bearing wear. Knock Sensor Detection System (KSDS) triggers limp mode and DTC P1326 but fails to prevent catastrophic engine failure. Bearings may fail despite soft warning indicators.
When: Typically 99,000–115,000+ miles; some earlier; one case post–knock sensor update installation
Symptoms owners cite: Loud knocking or ticking noise from engine under hood; Check engine light with DTC P1326 (knock signal range/performance); Vehicle enters limp mode unpredictably; Hard vibrations or engine roughness; Loss of power at highway speeds; Burning oil concurrent with knock noise
Codes mentioned: P1326, Related hybrid codes: U0293, U1004
Repairs/costs cited: Rod bearing clearance test: ~$140. Owners report knock sensor replacement under campaign 953; bearing clearance test may pass despite symptoms. Engine replacement: $11,400–$12,000+ quoted by dealerships.
Recalls/TSBs owners mention: Campaign 953 (KSDS software update and knock sensor installation/replacement). Service bulletins (TSB 22-01-023H cited). Extended warranty (Hyundai TXXI) tied to campaign completion. Many owners report Hyundai denies engine replacement citing mileage limits despite recall-related code P1326 and confirmed bearing damage.
Spark Plug / Ignition Coil Fouling & Repeated Failure
Spark plugs and ignition coils fail repeatedly (often monthly or every 100–1000 miles) due to oil pooling on plugs from excessive oil consumption. Owners must replace plugs multiple times per year at significant cost.
When: Concurrent with excessive oil consumption; some reports as frequent as monthly
Symptoms owners cite: Spark plugs and ignition coils fouled with oil or soot; Cylinders misfire after plug/coil replacement; Repeated failures despite recent replacement; Engine light and rough running following replacement
Codes mentioned: P0300 (random/multiple cylinder misfires), P0301–P0304 (specific cylinder misfires)
Repairs/costs cited: Spark plug replacement: $100–$700 per service depending on parts/labor. Ignition coil replacement: included in plug service. Owners report repeated replacement—sometimes monthly. Dealerships ultimately decline repair (advising plug replacement won't resolve underlying oil burn) and recommend engine replacement.
Recalls/TSBs owners mention: No manufacturer-level response for plug fouling documented. Dealerships perform replacement under general maintenance; Hyundai denies extended warranty coverage for plug damage tied to oil consumption in out-of-warranty vehicles.
Valve Cover Gasket & Rear Main Seal Leaks
Engine leaks oil from valve cover gaskets and rear main seal. Gaskets may be replaced multiple times without resolution, and oil may leak into spark plug tubes and engine bay.
When: Variable; one case first reported at ~27,000 miles into ownership after early oil service problem
Symptoms owners cite: Oil dripping from engine compartment or under hood; Oil leaking into spark plug tubes; Engine light and misfiring following oil intrusion; Recurrent leaks after gasket replacement
Repairs/costs cited: Valve cover gasket replacement: dealership performed twice in one case with no permanent resolution. Rear main seal repair: mentioned but full repair details sparse.
Recalls/TSBs owners mention: No specific campaign or recall documented for gasket leaks. Repairs conducted as general warranty work; denials occur for vehicles outside warranty coverage.
Catastrophic Engine Failure / Engine Seizure
Engine seizes, locks up, or suffers internal mechanical failure (metal shavings, rod bearing wear, piston damage) requiring complete engine replacement. Failures often sudden and without prior diagnostic codes.
When: Variable; some occur after mild symptoms (oil consumption), others suddenly without warning; mileage 55,000–140,000+
Symptoms owners cite: Engine seizes or locks (no rotation); Loss of power and stalling without warning; Metal shavings discovered by dealership during inspection; No compression in one or more cylinders; Engine rattling or severe knocking preceding failure
Codes mentioned: Code P0300 (misfires preceding failure), Metal shavings/debris found during inspection
Repairs/costs cited: Complete engine replacement required. Costs: $3,880–$12,000. Dealership diagnostic for tear-down: $498–$672. Owners report months-long waiting periods (2–6+ months) while vehicle sits at dealership; many denied warranty coverage.
Recalls/TSBs owners mention: Extended warranty programs (TXXI, class action settlements) cited but frequently denied for vehicles outside recall scope or mileage/time limits. Some cases: Hyundai offers buyback or small cash settlement instead of engine replacement. Warranty claims often denied pre-emptively before service records reviewed.
Limp Mode / Safety Mode Unintended Activation
Vehicle suddenly enters limp mode or safety mode without prior warning, restricting power to 30–60 mph on highway. Activation may be tied to knock sensor malfunction, engine control module issues, or other electrical faults. No pre-warning allows driver to safely decelerate.
When: Variable; often unpredictable; one case triggered post–software recall update
Symptoms owners cite: Vehicle suddenly limits speed to 30–60 mph without warning; Check engine light and/or safety mode indicator illuminate; Loss of acceleration or responsiveness; Hazardous driving situations (highway traffic, inability to merge); May recur multiple times within days or weeks
Codes mentioned: P1326 (knock sensor/bearing related), Software-related codes post-update
Repairs/costs cited: Dealership performs software updates (recall campaign 953), knock sensor replacement, or engine diagnostic. No permanent fix documented for chronic limp mode in several cases.
Recalls/TSBs owners mention: Campaign 953 software update intended to detect and mitigate rod bearing wear but fails to prevent limp mode in many vehicles. Some owners report Hyundai refuses to reverse software update even after it triggered limp mode condition.
Engine Fire / Extreme Overheat Condition
Vehicle catches fire while parked or driving, consumed by flames. One case: white smoke observed from under hood 75 miles before fire; fire department unable to save vehicle. Possible ignition source: oil saturation, catalytic converter damage from excessive oil consumption, or internal heat.
When: One documented case: ~90,000 miles; white smoke warning 75 miles prior
Symptoms owners cite: White smoke from under hood; Vehicle engulfed in flames while parked; Fire uncontrollable by portable fire extinguishers
Repairs/costs cited: Vehicle total loss; condemned by insurance. Fire department response; police report filed.
Recalls/TSBs owners mention: Manufacturer not notified in documented case. No recall or campaign tied to engine fire risk identified in complaint narratives.
Catalytic Converter Clogging / Damage
Excessive oil consumption causes oil to foul and clog catalytic converter, reducing exhaust flow and creating back pressure. One owner reports removing catalytic converter packing to allow exhaust escape; converter temp reached 1700°F.
When: Concurrent with prolonged oil consumption; one case noted after months of excessive burning
Symptoms owners cite: Catalytic converter overheating (temperatures cited: 1700°F); Exhaust fumes entering passenger cabin or backing into engine; Reduced engine performance tied to exhaust restriction; Check engine light (P0420 catalytic converter code)
Codes mentioned: P0420
Repairs/costs cited: Catalytic converter replacement: performed by independent mechanic; dealership did not authorize repair. One owner reports physically removing converter packing as workaround.
Recalls/TSBs owners mention: No manufacturer coverage for catalytic converter damage tied to oil consumption when vehicle outside warranty.
Oil Consumption Test Delays & Repair Authorization Denials
Dealerships and Hyundai use mandatory oil consumption testing (1000-mile intervals) to delay or deny engine replacement claims. Owners must repeatedly bring vehicle in, pass multiple rounds of testing, and still face denials. Process takes months; some vehicles undergo 3–6+ test cycles without resolution.
When: Variable; some cases span 6+ months of testing
Symptoms owners cite: Dealership requires 1000-mile oil consumption test before considering repair; Multiple test cycles (2–6+ rounds) required; No oil leak detected but oil continues to disappear; Hyundai corporate denies claim despite test confirmation of excessive consumption
Repairs/costs cited: Oil consumption test: repeated every 1000 miles. Combustion chamber cleaning: $500–$672, attempted between tests. No reimbursement or loaner cars provided during extended testing periods.
Recalls/TSBs owners mention: Hyundai corporate and dealerships cite testing protocol and mileage/warranty limits as basis for denials. Some owners report dealerships fail to submit test results to corporate or lose documentation. Process designed to delay resolution until warranty expires.
Warranty Denial & Out-of-Scope Coverage Claims
Hyundai and dealerships deny warranty coverage, engine replacement, or repair based on mileage (exceed 100,000–150,000 miles), age (exceed powertrain warranty), or vehicle being out of recall scope. Owners with documented defects and service records still denied despite class action settlements or extended campaigns.
When: Upon diagnosis of defect (timing variable depending on vehicle age/mileage)
Symptoms owners cite: Engine failure diagnosed; warranty claim submitted; Denial letter citing vehicle outside recall or warranty scope; Dealer-authorized repair denied despite service bulletins issued
Repairs/costs cited: Denied claims for: engine replacement ($3,880–$12,000), rental car reimbursement, diagnostic fees ($498–$700), and combustion cleaning.
Recalls/TSBs owners mention: Hyundai denies coverage citing: (1) vehicle outside mileage limit (e.g., >100K miles), (2) VIN not listed in recall campaign, (3) extended warranty lapsed, (4) settlement agreement restrictions, (5) previous owner or third-party service disqualifies claim. Some cases: Hyundai offers buyback at depreciated value instead of repair (one case: $6,000 buyback for car valued at $17,000 by dealership 18 months prior).
Synthesized from 292 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 9 most recent
My 2017 Hyundai Sonata Sport Limited 2.4 has a known engine defect causing excessive oil consumption. The vehicle was at an authorized Hyundai dealership for the oil consumption test and had been approved for a new engine replacement. Prior to the repair, I completed $2,300 in maintenance, specifically an oil combustion cleaning and spark plug replacement, which the dealership said was required…
In winter of 2018, my husband and I purchased a certified pre-owned 2017 Hyundai Sonata, and from the moment we drove it off the lot, it had an oil consumption problem. Then, in 2023, the spark plugs began failing. Each time this happens, the whole car shakes and stops running. We found out that Hyundai and Kia engines from 2009-2022 have major problems and that there are many class-action…
The contact owns a 2017 Hyundai Sonata. The contact stated while driving 45 MPH and depressing the accelerator pedal, the RPMs revved up however, the vehicle failed to respond. The contact stated that the vehicle decelerated, lost motive power and stalled in the middle of the road. The contact's newborn and two other young children were occupying the rear seats at the time the failure occurred.…
While I was driving I had come to a stop at the stop light. When it turned green I began to make a left turn. Halfway through the turn at a few miles an hour my engine light and traction control lights came on. At the same time the engine began to rev to about 4500 RPM. It died down quickly. I then had no response from the accelerator. Luckily I was able to pull over to the side of the road as I…
Car is leaking oil and burning oil ..had oil changed recently and it is below the full mark
Se consume el aceite en periodo de 8 días, Se quemas las bujias El carro tiembla Sale en pantalla el botón amarillo del motor que hay falla Ya me ha pasado varias veces ando con mis dos hijos menores de edad en autopista y ya he quedado varada en varias oportunidades y esto me está generando un gran riesgo estoy hubicada en jacksonville florida
Excessive oil consumption Engine light stays on. Noise in Engine GDI 2.4
2017 Hyundai Sonata with Theta II engine received knock sensor detection software update 7/30/19. Engine knock increased substantially during August and September of 2022 with periodic, partial loss of power at idling and significant oil consumption. Dealership initiated oil consumption testing 9/24/22. On 11/2/22, vehicle fully stalled with blue smoke from exhaust during slow-speed turn in…
I have a recall Hyundai doesnt want to fix did a total of 10 oil consumption test but my car keeps burning oil also my car has also shut off in the middle of driving it. Multiple times I also found out my vehicle had a recall this year not last year they claimed that they put a device on my vehicle but I was unaware of it
Had engine trouble with your 2017 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 2017 Hyundai Sonata?
It's a documented issue but not catastrophic. 292 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 77 complaints that reported odometer mileage, most engine failures cluster between 54,000 and 115,000 miles, with the median around 82,000. A quarter of owners report trouble before 54,000; a quarter make it past 115,000. 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/2017/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.