Frequently Asked Questions

What is the most common reason for check engine light on a 2025 GMC Sierra 3500HD?

• Common causes include a loose or damaged gas cap, faulty oxygen sensor, ignition misfires (plugs or coils), EVAP leaks, or mass airflow sensor issues.
• Loose gas caps are inexpensive to fix but can trigger persistent codes and reduced fuel economy if ignored.
• Misfires or sensor failures can lead to catalytic converter damage if left unaddressed—raising repairs from tens to thousands of dollars.
• Our dealership’s factory-trained techs identify root causes quickly, minimizing long-term costs and protecting vehicle value.

What does it mean when the check engine light comes on in a 2025 GMC Sierra 3500HD?

• It signals that the vehicle’s onboard diagnostics detected a fault—ranging from minor emissions issues to serious engine problems.
• A steady light usually means a non‑urgent trouble code; a flashing light indicates active misfire or severe fault that needs immediate attention.
• Only a diagnostic scan reveals the specific code and severity; our dealership uses OEM tools and software for accurate analysis.
• Repairs covered under warranty must be performed at a certified dealership to preserve coverage and ensure genuine parts are used.

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

• Start with simple checks: ensure the gas cap is tightened properly and inspect for obvious fuel or fluid leaks.
• Note vehicle behavior—loss of power, rough idle, or strange noises—and tell the service advisor when you schedule an appointment.
• If the light is flashing or you experience performance loss, stop driving and have the truck towed to our dealership to avoid further damage.
• For warranty protection and long-term savings, have diagnostics and any covered repairs completed at a certified dealer like ours.

How much does a check engine light diagnostic cost for a 2025 GMC Sierra 3500HD?

• Basic diagnostic scans at our dealership typically start in a modest range—many customers see a straightforward scan fee, with labor and parts quoted separately after diagnosis.
• Some issues require parts and additional labor; estimated repairs can range from a small parts replacement to more extensive work if catalytic or engine damage is found.
• Coggin Buick/GMC of Orange Park often costs less than independent shops while delivering factory-level service—providing immediate savings and reducing future repair risk.
• Remember: repairs covered under warranty must be performed at a certified dealer to maintain coverage and avoid out-of-pocket long-term costs.

How long does a check engine light service take?

• Initial diagnostic scans typically take 30–90 minutes depending on symptom complexity and system access.
• Minor fixes—like tightening a gas cap or replacing a sensor—are often same-day; more involved repairs may require parts ordering and can take a day or longer.
• Our parts department and factory-trained technicians help expedite repairs to reduce downtime and deliver long-term savings versus repeated or incomplete fixes.
• If the issue is covered by warranty, repairs must be completed at a certified dealership; we coordinate approvals to streamline the process.