What does it mean when the check engine light comes on in a 2021 Hyundai Sonata?

• It indicates the vehicle’s onboard diagnostics detected an issue — anything from a loose gas cap to an emissions or engine sensor fault. Our certified Hyundai technicians at Larry H. Miller Hyundai Peoria diagnose the cause quickly and accurately.
• We often find simple fixes first (sensors, emissions-related parts, or electrical connections). Choosing the dealership for repairs can deliver immediate and long-term savings thanks to OEM parts, proper repair procedures, and service warranties that reduce repeat visits.
• If a repair is covered under warranty, it must be completed at a certified dealership to preserve protection. We honor warranties and clearly explain coverage before any work begins.
• We offer service financing so you can get service now and pay later, preserving your safety and preventing small issues from becoming costly failures.
• Ready to act? Please schedule service or check our service specials before you visit for added value.

How long does a check engine light service take?

• Diagnostic scans are typically completed within 30–60 minutes depending on complexity; many issues are identified and prioritized the same day at Larry H. Miller Hyundai Peoria.
• Repairs vary — quick fixes (loose cap, sensor replacement) can often be completed in an hour; more involved work (catalytic, wiring, or multiple component repairs) may require parts ordering and a longer appointment.
• Our factory-trained technicians use OEM parts and manufacturer procedures to ensure correct repairs the first time, delivering both immediate reliability and long-term savings in fuel economy and avoidance of secondary damage.
• We make scheduling easy — schedule appointment online, view current offers on our service specials, and ask about service financing to spread payments.

How much does a check engine light diagnostic cost for a 2021 Hyundai Sonata?

• Diagnostic pricing varies, but at Larry H. Miller Hyundai Peoria our diagnostic rates are competitive and often cost less than independent shops while delivering factory-trained expertise and comprehensive inspection reports.
• You save immediately through accurate diagnosis, OEM repairs, and access to genuine parts that prevent recurring faults; long-term savings come from avoided engine damage and preserved fuel efficiency.
• We publish current discounts under service specials and offer service financing so you can address problems without delay.
• Remember that warranty-covered repairs must be completed at a certified dealership to remain valid; our advisors will explain any warranty or coverage before work begins.

What is the most common reason for check engine light on a 2021 Hyundai Sonata?

• The most frequent causes are loose fuel caps, oxygen sensor faults, or catalytic converter and EVAP system issues. Many of these affect emissions and fuel economy if left unresolved.
• Addressing codes promptly at Larry H. Miller Hyundai Peoria protects engine components, maintains fuel efficiency, and avoids extended repairs. Our technicians provide a clear estimate and timeline so you can make informed decisions.
• We emphasize transparency: you get a full explanation, cost estimate, and options — including OEM parts and warranty coverage — plus access to our service specials to reduce out-of-pocket cost.
• To keep your Sonata running its best, schedule service with our service center and ask about maintenance plans and financing options.

What is the first thing to check when the check engine light comes on?

• Begin with the basics: check the gas cap to ensure it’s tightened properly. A loose cap can trigger an EVAP code and is an easy fix our technicians confirm during the initial diagnostic.
• If the light persists or flashes, bring the vehicle to Larry H. Miller Hyundai Peoria immediately — flashing lights can indicate severe misfires that risk catalytic converter damage and reduced safety.
• We provide a full scan, clear explanation of required repairs, and recommendations that favor long-term vehicle health. Repairs covered under warranty must be performed at a certified dealership to preserve coverage.
• Use our online tools to schedule service or check current service specials to save on maintenance and repairs.

2021 Hyundai Sonata Check Engine Light Reset

The process to reset the check engine light on a 2021 Hyundai Sonata begins with a proper diagnostic scan to identify the root cause instead of simply erasing the code. At Larry H. Miller Hyundai Peoria in Peoria, AZ, our technicians use OEM-grade scanners that reveal pending and stored trouble codes, freeze-frame data, and real-time sensor readings. Resetting the light without addressing the underlying fault risks recurrence and can mask conditions that lead to more costly repairs — our team prioritizes fixes that restore performance, emissions compliance, and fuel economy. We follow Hyundai-recommended procedures, install genuine parts when needed, and document the repair so your vehicle history and any applicable warranties remain intact. Customers appreciate our transparency: you’ll receive an itemized estimate, a clear explanation of why the light activated, and expected cost and labor timelines. We offer service financing to help you complete necessary repairs without delay, and our website lists current service specials to maximize savings. To ensure the right repair and preserve warranty coverage, schedule service with our factory-trained team at Larry H. Miller Hyundai Peoria today.

2021 Hyundai Sonata Check Engine Light Codes

Common check engine light codes on a 2021 Hyundai Sonata include P0420 (catalyst efficiency), P0130–P0167 (oxygen sensor and heater circuits), P0440–P0455 (EVAP system leaks), and P0300–P0304 (engine misfires). Each code points to a different severity and potential cost if left unresolved: EVAP leaks can reduce fuel efficiency and trigger emissions test failure; oxygen sensor issues left unattended accelerate catalytic converter wear and may lead to expensive replacement; misfires can harm the catalytic converter and cause rough running that escalates repair costs. At Larry H. Miller Hyundai Peoria in Peoria, AZ, we handle these diagnoses with manufacturer tools, rapid parts sourcing, and trained technicians who prioritize long-term ownership value. Choosing our dealership often means lower overall cost compared with fragmented repairs — we focus on lasting fixes using OEM parts, clear warranties, and service financing so you can get repairs started immediately and pay over time. We also promote preventive maintenance through our service plans and seasonal service specials. For accurate, fast diagnostics and confidence in the repair, schedule appointment online and let our certified technicians restore your Sonata to peak condition.

Check Engine Light Flashing

A flashing check engine light on a 2021 Hyundai Sonata usually indicates an active engine misfire or other condition that can cause catalytic converter overheating and immediate drivability issues. This is one of the few scenarios where you should stop driving if possible and have the vehicle evaluated right away to prevent costly downstream damage. At Larry H. Miller Hyundai Peoria, we treat flashing lights as urgent: our service advisors prioritize these appointments, perform a rapid diagnostic, and explain repair options and costs up front. We also offer service financing to help you address urgent repairs without delay, and our service center frequently posts money-saving service specials to lower immediate expenses. Choosing our dealership ensures repairs are completed by Hyundai-certified technicians using OEM parts and backed by appropriate warranties — and warranty repairs must be done at certified dealerships to remain valid. Protect your vehicle and wallet: schedule service online or contact Larry H. Miller Hyundai Peoria to speak with our team and get same-day or next-available appointments.