Service Brakes / Brake Assist Failure

Frequent complaints involve stiff brake pedals, failure to stop effectively, and 'Service Brake Assist' warnings. This is often linked to the **brake vacuum pump** and its related components, which can fail prematurely. Some reports suggest engine damage can occur if the vacuum pump failure is prolonged. Estimated repair cost: $500 - $1,500.

Engine Stalling / Loss of Power

Owners report unexpected engine stalling, jerking, and significant loss of power, sometimes without warning lights. Issues with the **engine control module (ECM)**, fuel system, or turbocharger (on the 2.0L engine) are common culprits. Early-life failures have been noted. Estimated repair cost: $400 - $1,200.

Electrical System Malfunctions

Varied electrical issues are reported, including problems with the infotainment system, door locks, and intermittent power loss. These can stem from faulty **wiring harnesses**, control modules, or battery issues. Some complaints point to potential design flaws. Estimated repair cost: $200 - $1,000.

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2018 GMC Terrain Maintenance guide

Name: Maintenance dataset for 2018 GMC Terrain
Creator: Carfocal

v1.0Updated May 30, 2026Daniel Wilson4 Sources Analyzed3 Critical Recalls

MAINTENANCE SUMMARY

The 2018 GMC Terrain, with a 'Below Average' reliability verdict, demands diligent maintenance. Owners should prioritize inspections for brake system issues, particularly vacuum pump failures, and engine/powertrain concerns, which are frequent and critical.

View Critical Issue: Powertrain / Transmission Issues

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Reliability Score

Est. Annual Maintenance Cost

$400 - $800

TSBs & Recalls

563 TSBs | 5 Recalls

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Key Takeaways

Prioritize inspection and maintenance of the brake system, particularly the vacuum pump.
Address engine and powertrain performance anomalies promptly to prevent costly failures.

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Critical service intervals

Common failure analysis

Symptoms and prevention guidance