Frequently Asked Questions

What is the most common reason for check engine light on a 2018 Toyota Mirai?

• Common causes include sensor faults (oxygen or temperature sensors), catalytic efficiency alerts, and electrical or software errors in the fuel‑cell management system.
• On a hydrogen fuel‑cell vehicle like the 2018 Toyota Mirai, control module or emissions‑system messages are typical and can be cleared quickly when diagnosed properly.
• If left unaddressed, small sensor problems can escalate to more expensive repairs; early dealer diagnostics often reduce long‑term cost.
• Warranty repairs must be completed at a certified dealership to remain covered and to ensure factory‑trained technicians perform the work.
• At Nalley Toyota of Roswell we often cost less than independent shops while delivering factory‑level service and genuine parts.

How long does a check engine light service take?

• Typical diagnostic appointments take about 1 to 2 hours for a full scan and initial inspection; complex repairs will require additional time.
• Our factory‑trained technicians use OEM equipment to speed accurate diagnosis and avoid repetitive repairs that drive up long‑term costs.
• When warranty work is required, diagnostics and repairs performed at our certified dealership preserve coverage and often lower total ownership cost.
• We provide clear time estimates before work begins and offer service specials to maximize immediate and long‑term savings.

What does it mean when the check engine light comes on in a 2018 Toyota Mirai?

• An illuminated check engine light signals the vehicle’s onboard diagnostics detected an abnormal condition — from minor sensor issues to more serious fuel‑cell or control system faults.
• It does not always mean immediate danger, but it does require prompt diagnosis to prevent further damage or reduced efficiency.
• Bringing your Mirai to a certified dealer ensures correct troubleshooting, genuine parts, and warranty protection when applicable.
• Nalley Toyota of Roswell often provides lower overall repair costs than independent shops by avoiding repeat visits and securing OEM parts and procedures.

How much does a check engine light diagnostic cost for a 2018 Toyota Mirai?

• Diagnostics at our service center typically start around $89 and can range up to $149 depending on the depth of testing required.
• That initial fee covers a full scan, visual inspection, and a technician’s recommendations; additional repairs are quoted before work begins.
• Choosing our dealership often yields immediate savings through accurate diagnosis and long‑term savings by preventing unnecessary repairs that independents might recommend.
• Remember: warranty repairs must be completed at a certified dealership to retain coverage and to ensure safe, compliant service on hydrogen vehicles.

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

• First, look for secondary warnings on the dash, listen for unusual noises, and note any changes in drivability or power delivery.
• A quick visual check for obvious issues—loose connections, fluid leaks, or dashboard messages—can help, but it won’t replace a full diagnostic.
• Because the 2018 Toyota Mirai is a hydrogen fuel‑cell vehicle, specialized inspection and safety procedures are critical and are best handled at a certified dealership.
• Bring your vehicle to Nalley Toyota of Roswell for prompt diagnostics; our factory‑trained techs preserve warranty coverage and deliver both immediate and long‑term savings.