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 ↗2018 Hyundai Tucson electrical problems
severe Owners of the 2018 Hyundai Tucson have filed 20 NHTSA complaints about the electrical at roughly $850 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See electrical across all vehicles →
Complaints
20
Recalls
0
Avg fix
$850
| Model year | electrical complaints |
|---|---|
| 2014 Tucson | 12 |
| 2015 Tucson | 17 |
| 2016 Tucson | 159 |
| 2017 Tucson | 65 |
| 2018 Tucson (this page) | 20 |
| 2019 Tucson | 36 |
| 2020 Tucson | 16 |
| 2021 Tucson | 9 |
| 2022 Tucson | 41 |
2crashes
2injuries
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering electrical 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 a loss of connectivity or interruptions in the middle of using Bluelink Service functions. This may be due to an irregular disconnection on Verizon’s communication network. Follow the procedure in this TSB to reestablish the connection via the AVN pinhole reset method.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners of 2018 Tucsons cite electrical and powertrain defects that pose genuine safety risks. Headlights and taillights fail repeatedly—one owner replaced bulbs at least 12 times in 6 years, with melted wiring in the assemblies. Taillights melt in their sockets; bulb-out warnings persist even after replacement.
Engine seizure without warning is the most severe complaint. Multiple owners describe the engine stopping cold on highway, with no warning lights beforehand. One bought the vehicle used at 118,000 miles and had to add oil weekly before failure; another had only 1,167 miles on a "new" purchase when the engine seized, leaving them stranded on a major highway.
Electrical power cuts out mid-drive: one owner lost all systems at 1,167 miles—no phone, no steering assist, complete dead stop. Turn signals fail sporadically mid-turn. Infotainment screens go black. Battery lights come on and vehicles shut off in motion.
Transmission hesitation in stop-and-go traffic is reported as a "known problem" at dealerships, yet promised repairs never arrived. One owner stalled just 3 feet forward from a complete stop.
Secondary issues include rodent damage to soy-based wiring insulation, cooling fans running hours after engine shutdown, and one case of airbag failure to deploy in a 70-mph collision with a deer.
Dealership handling is a common frustration. Known defects are dismissed as "cannot duplicate," repairs are delayed for months, and owners are left with vehicles out of service for weeks. Some report being denied warranty coverage, only to have it honored after escalation.
Same Hyundai Tucson electrical reports on nearby years: 2015 · 2016 · 2017 · 2019 · 2020
Failure modes owners describe
Headlight and taillight failures with socket melting
Bulbs fail repeatedly; taillights melt in sockets. One owner reported 12+ bulb replacements over 6 years, persistent 'bulb out' warnings, and eventual headlamp assembly replacement due to melted wiring.
When: 2019 onwards; one case 6 times in 12 months
Symptoms owners cite: Repeated bulb burnout; Persistent bulb-out warning lights; Melted wiring in headlamp assembly; Taillights melting in socket
Repairs/costs cited: Headlamp assembly replacement (2025); bulb replacements (~6–12 over time); socket replacement recommended by owners
Recalls/TSBs owners mention: Initial dismissal as 'could not duplicate' (April 2023); eventual assembly replacement after escalation to Corporate
Engine seizure and sudden failure
Multiple owners report engine seized without warning, at or near highway speeds, after regular maintenance. One case at 118,000 miles with weekly oil loss; another at 1,167 miles on a new purchase. No warning lights before failure in most cases.
When: Various: 118,000 miles; 1,167 miles; unspecified mileages
Symptoms owners cite: Engine seized or stopped running without warning; Sudden loss of power while driving; No warning lights before failure; Heavy oil consumption (1 quart/week in one case); Burning smell; Engine shaking
Repairs/costs cited: Engine replacement required (2023 case); complete motor failure confirmed by independent shops
Recalls/TSBs owners mention: Owners allege Hyundai knowingly sells vehicles with this defect; one case mentions class-action lawsuit awareness
Engine stalling and electrical shutdown while driving
Electrical components and engine power fail intermittently during operation. One case involved radio/turn signal dying mid-turn; another involved complete power loss on highway with 1,167 miles on vehicle.
When: Varied; one at 1,167 miles
Symptoms owners cite: Sudden complete power loss on highway; Radio and dash electronics shutting off; Turn signal failing mid-turn; Vehicle stalling in motion; Bad ground wire (one diagnosis)
Repairs/costs cited: One case diagnosed as bad ground wire; no other repairs specified
Transmission/engine hesitation in stop-and-go traffic
Vehicle jerks or jumps in slow-speed traffic, resembling clutch engagement problems. Reported at 3 dealerships; one stated it was a 'known problem' with a fix coming (never arrived). Low-speed stall risk.
When: Intermittent, occurs during slow-speed driving
Symptoms owners cite: Jerking or jumping sensation in stop-and-go traffic; Complete stop after moving ~3 feet from standstill; Resembles manual transmission clutch grab
Repairs/costs cited: Dealerships unable to replicate; Bob Mayberry Hyundai (Monroe, NC) confirmed as known problem; promised fix never materialized
Recalls/TSBs owners mention: Acknowledged as known problem at dealership level; promised repair part in March/April 2020 but owner never contacted and no resolution provided
Turn signal switch failure
Left turn signal stops working sporadically during left turns, then resumes after turn is complete. Safety hazard if signal fails mid-turn.
When: Sporadic over several months
Symptoms owners cite: Left turn signal fails intermittently during turn; Signal resumes after turn completes
Repairs/costs cited: Multifunctional turn signal switch replacement
Recalls/TSBs owners mention: Repair covered under extended warranty
Cooling fan or blower running after engine shut off
High-pitched electrical noise (like an electric dryer) heard from parked vehicle hours after engine turned off, with air movement felt in engine bay. No prior warning or dashboard indicator.
When: Occurred 7-8 hours after engine shutdown
Symptoms owners cite: Loud electric noise from engine bay after engine off; Air movement in engine compartment; No warning dashboard lights; Risk of fire concern
Battery/charging system warning light
Battery warning light illuminates; in one case vehicle shut off while in motion on main road. Related to electrical defects.
When: Unspecified timing
Symptoms owners cite: Battery light coming on; Vehicle shutdown while in motion; Electrical system failure
Multiple warning lights (check engine, oil, tire pressure)
Several warning lights illuminate simultaneously on instrument panel, suggesting electrical or sensor malfunction.
When: Timing unspecified
Symptoms owners cite: Check engine light; Oil pressure warning light; Tire pressure warning light
Repairs/costs cited: Vehicle not diagnosed or repaired by owner
Rodent-damaged soy-based wiring insulation
Engine light activation due to rodent chewing of soy-based wiring insulation. Occurred twice in one year. Owner cites safety concern with wiring material choice.
When: Twice over one year
Symptoms owners cite: Check engine light; Chewed wires and insulation in engine bay
Repairs/costs cited: Wiring repair cost $600+
Recalls/TSBs owners mention: Owner requests recall on soy-based wiring coating
Media screen/infotainment system failure
Navigation, radio, and media screen went black and would not power on. Vehicle also experienced sluggish starting and shaking/rattling during startup and shutdown.
When: April 2024; another case November 2023–April 2024
Symptoms owners cite: Media/navigation screen goes black; Screen will not turn on; Sluggish engine behavior; Difficult first-attempt starting; Car shaking/rattling on startup and shutdown
Repairs/costs cited: Required dealership tow; no repair details provided
Engine sluggishness and irregular shifting after collision
Post-collision, engine became very sluggish with irregular shifting and slight ticking. Battery light came on; engine shut off on main road. Dealership deemed total loss with blown engine.
When: Post-collision; vehicle 2 years old, <50,000 miles
Symptoms owners cite: Engine sluggish after collision repair; Irregular transmission shifting; Slight ticking in engine block; Battery light illumination; Engine shutdown on main road
Repairs/costs cited: Dealership declared total loss; engine blown
Airbag failure to deploy in high-speed collision
Airbags did not deploy when vehicle struck a large deer at 70 mph on main highway, despite significant impact.
When: Post-70-mph collision with deer
Symptoms owners cite: Airbags failed to deploy on impact
Burning smell from HVAC system
Burning odor detected from vehicle heating system during cold weather, emanating from ventilation. Subsided when heater lowered.
When: Post-purchase (December 2021); reported January 2022
Symptoms owners cite: Burning smell from HVAC vents; Smell intensity varies with heat setting
Synthesized from 20 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 0 most recent
Had electrical trouble with your 2018 Hyundai Tucson?
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 electrical problem on the 2018 Hyundai Tucson?
It's a meaningful issue. 20 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $850.
At what mileage does the electrical typically fail?
Based on the 20 complaints filed, electrical issues most often appear around 20,548 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $850 for electrical 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 electrical?
No active recalls currently cover electrical 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/2018/Hyundai/Tucson.
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.