2018 GMC Sierra
The 2018 GMC Sierra 1500 is a full-size pickup truck known for its comfortable ride, strong towing capabilities, and refined interior (especially in higher trims). Engine options include a 4.3L EcoTec3 V6 (285 hp, 305 lb-ft of torque), a 5.3L EcoTec3 V8 (355 hp, 383 lb-ft of torque), and a 6.2L EcoTec3 V8 (420 hp, 460 lb-ft of torque). Transmission options include a 6-speed automatic (paired with the 4.3L V6 and some 5.3L V8 models) and an 8-speed automatic (paired with some 5.3L V8 models and the 6.2L V8). Owners often praise the Sierra’s comfortable ride, powerful engine options, and user-friendly technology. Common complaints include transmission issues (specifically with the 8-speed), occasional electronic glitches, and higher repair costs compared to some competitors.
Engine
4.3L EcoTec3 V6
- Active Fuel Management (AFM) Lifter Failure
- Description/Symptoms: Engine misfires, rough idling, check engine light illuminated (typically with codes related to cylinder deactivation). This is caused by a failure in the AFM lifters which prevent a cylinder from receiving fuel causing the engine to run improperly.
- Solution: Replacement of the faulty AFM lifters, and potentially the camshaft if damage has occurred. Some owners opt for a full AFM delete kit.
- Estimated Cost to Fix: $2,500 - $4,000+
- Recalls: None Found
5.3L EcoTec3 V8
- Active Fuel Management (AFM) Lifter Failure
- Description/Symptoms: Engine misfires, rough idling, check engine light illuminated (typically with codes related to cylinder deactivation). This is caused by a failure in the AFM lifters which prevent a cylinder from receiving fuel causing the engine to run improperly.
- Solution: Replacement of the faulty AFM lifters, and potentially the camshaft if damage has occurred. Some owners opt for a full AFM delete kit.
- Estimated Cost to Fix: $2,500 - $4,000+
- Recalls: None Found
- Oil Consumption
- Description/Symptoms: Excessive oil consumption between oil changes, blue smoke from the exhaust, and potential engine damage due to low oil levels.
- Solution: Installation of a redesigned valve cover, replacement of piston rings.
- Estimated Cost to Fix: $300 - $500 (valve cover), $3,000 - $5,000+ (piston rings)
- Recalls: None Found
6.2L EcoTec3 V8
- Active Fuel Management (AFM) Lifter Failure
- Description/Symptoms: Engine misfires, rough idling, check engine light illuminated (typically with codes related to cylinder deactivation). This is caused by a failure in the AFM lifters which prevent a cylinder from receiving fuel causing the engine to run improperly.
- Solution: Replacement of the faulty AFM lifters, and potentially the camshaft if damage has occurred. Some owners opt for a full AFM delete kit.
- Estimated Cost to Fix: $2,500 - $4,000+
- Recalls: None Found
Transmission
6-Speed Automatic (6L80)
- No Issues Found
8-Speed Automatic (8L90)
- Harsh Shifting/Shuddering
- Description/Symptoms: Harsh shifting, shuddering, hesitation, and clunking noises, particularly during low-speed driving or when shifting between gears.
- Solution: Updated transmission fluid to a revised formula (Mobil Delvac 1 ATF), transmission flush, or replacement of valve body. In some cases, complete transmission replacement is required.
- Estimated Cost to Fix: $100 - $300 (fluid change), $500 - $1500 (valve body), $3,000 - $5,000+ (transmission replacement)
- Recalls: None Found
Suspension
- Premature Wear of Shocks/Struts
- Description/Symptoms: Bouncy ride, poor handling, excessive body roll, and clunking noises from the suspension.
- Solution: Replacement of worn shocks and/or struts.
- Estimated Cost to Fix: $300 - $800+ per axle
- Recalls: None Found
Electrical
- Infotainment System Glitches
- Description/Symptoms: Freezing, slow response times, screen flickering, Bluetooth connectivity issues, and navigation errors with the infotainment system.
- Solution: Software updates, resetting the system, or replacement of the infotainment unit.
- Estimated Cost to Fix: $0 (software update) - $1,000+ (infotainment unit replacement)
- Recalls: None Found
- Backup Camera Failure
- Description/Symptoms: Backup camera displaying a black screen, distorted image, or failing to activate at all.
- Solution: Check wiring connections, replace the camera module.
- Estimated Cost to Fix: $100 - $500+
- Recalls: None Found
Exterior
- Automatic Running Board Malfunction (If Equipped)
- Description/Symptoms: Automatic running boards failing to deploy or retract properly, getting stuck in one position, or making unusual noises.
- Solution: Lubrication of hinges and joints, replacement of the motor or the entire running board assembly.
- Estimated Cost to Fix: $50 - $200 (lubrication/minor repairs), $500 - $1,500+ (motor or assembly replacement)
- Recalls: None Found
Interior
- Seat Heater Failure
- Description/Symptoms: Seat heaters not working or only working intermittently.
- Solution: Check wiring connections, replace heating element or seat heater control module.
- Estimated Cost to Fix: $100 - $500+
- Recalls: None Found
Summary
The 2018 GMC Sierra 1500 has a number of issues that buyers should be aware of. The most significant of these issues is the transmission problems with the 8-speed transmission, and the Active Fuel Management (AFM) lifter failure in the 4.3L, 5.3L, and 6.2L engines, which can lead to costly repairs. Electrical glitches and suspension issues can also occur, but are less frequent and generally less expensive to address. Prospective buyers should have a pre-purchase inspection performed by a trusted mechanic, paying close attention to the transmission and engine health.