Frequently Asked Questions

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

• Confirm safety and vehicle behavior: if you notice loss of power, strange noises, or drivability issues, stop driving and contact us immediately.
• Check visible items: fuel cap seating (EV/FCV systems have different fueling concerns), obvious leaks, and warning messages on the dash.
• Record conditions: note when the light came on, driving conditions, and any symptoms to help our technicians diagnose quickly.
• Remember warranty rules: any repairs covered under warranty must be performed at a certified dealership to preserve coverage.

How long does a check engine light service take?

• Initial diagnostic scan and inspection typically take 30–90 minutes, depending on symptoms and required tests.
• If parts or deeper inspections are needed, total repair time can range from a few hours to multiple days; we provide clear estimates and timelines.
• We prioritize efficient service with factory tools and access to parts, often reducing turnaround compared to independent shops.
• Warranty-covered repairs must be done at a certified dealership to ensure proper documentation and long-term coverage.

What does it mean when the check engine light comes on in a 2025 Toyota Mirai?

• It indicates the vehicle’s onboard diagnostics detected a fault in emissions, fuel cell, electrical, or powertrain systems.
• Common causes range from minor sensor issues to more serious fuel cell stack or catalyst-related faults that require immediate attention.
• Our technicians run a full OEM diagnostic to identify codes, interpret hydrogen‑vehicle specifics, and recommend the correct repair path.
• For warranty-covered faults, repairs must be performed by a certified dealership to maintain coverage and ensure immediate and long-term savings.

How much does a check engine light diagnostic cost for a 2025 Toyota Mirai?

• Diagnostic fees vary; many checks start with a standard scan fee and inspection. We provide transparent estimates before work begins.
• Nalley Toyota of Roswell often costs less than independent shops while delivering factory-level service and genuine parts, producing immediate and long-term savings.
• If repairs are covered under warranty, work must be completed at a certified dealership to retain coverage and avoid out-of-pocket expense.
• Ask about current service specials and our quick online scheduling to reduce downtime and cost.

What is the most common reason for check engine light on a 2025 Toyota Mirai?

• Common triggers include sensor faults (oxygen, pressure, temperature), electrical connectors, or emissions system anomalies.
• On hydrogen fuel cell vehicles, additional causes can involve fuel system sensors, hydrogen fueling system alerts, or catalyst efficiency readings.
• Left unaddressed, small sensor faults can escalate to more expensive repairs; dealer diagnostics identify root causes and prevent costly damage.
• Remember: warranty-covered repairs must be performed at a certified dealership to keep coverage and reduce lifetime ownership cost.