GMC Sierra 1500
2.7L turbo four, aluminum block, direct injection only — GM's answer to Ford's EcoBoost. 310 hp, 400 lb-ft from 1,500 rpm. Feels like a small V8 until the revs climb and the four-cylinder character shows. Head gasket failures on 2019-2022 early production under 25k miles, warranty-covered. A fleet of 750+ trucks at 50-80k miles with zero engine failures suggests the 2022+ builds are sorted.
2.7T in a Sierra — a hard sell at Denali prices
The 2.7 turbo-four makes sense in a $45k Silverado work truck. In a $65k Sierra Denali, the four-cylinder drone at highway speed undermines the premium positioning. 310 hp and 400 lb-ft are adequate, not inspiring. Buyers who chose this over the V8 usually regret it by the first towing trip.
Engine Weaknesses 5
Head gasket fails on early L3B under 25k miles. Covered under warranty.
Symptoms: White smoke, overheating, milky oil
Poor oil quality or extended intervals destroy turbo bearings.
Symptoms: Turbo lag, whine, blue smoke, power loss
Fuel injectors wear or fail — incorrect ECM programming (2019-2022) causes wrong injection quantity. Service Update N242450631 available as free fix.
Symptoms: Rough idle, misfires, poor fuel economy, check engine light
Piston rings let oil past — 0.75 to 1.75 quarts per 3,000 miles in documented cases. GM in one case rebuilt engine after two years of oil consumption. Often from ~30k miles.
Symptoms: Dropping oil level, blue smoke, oil consumption 0.5+ quarts per 600 miles
Direct injection only — walnut blasting from ~60k miles.
Symptoms: Rough idle, power loss
Vehicle Weaknesses 6
Corroded sub-frame ground strap causes simultaneous power steering and brake assist failures. Wiring harness chafing on ECM causes limp mode. Same platform issue as Silverado T1XX.
10L80 transmission develops harsh shifts and shudder. Multiple class actions filed. GM fluid flush (Mobil 1 LV ATF HP) helps temporarily. Severe cases require torque converter or complete transmission replacement under warranty extension.
Factory wax coating peels off frames within months of purchase. Visible surface rust on new trucks. GM issued service bulletin acknowledging the issue. Same problem across all T1XX platform trucks (Sierra, Silverado).
Shift to Park warning appears with transmission already in Park. Key gets stuck, battery drains overnight. Caused by worn shift cable bushing or electronic gear selector contact issue.
Sierra-exclusive MultiPro 6-way tailgate has actuator latch failures (micro-switch sends false signal), hinge binding, and step deployment issues. Load stop does not lock open. Exposed mechanisms vulnerable to dirt, ice, and salt. PIT5895A TSB for 2022 refresh disable function. Warranty covers most failures but repeat visits common.
Power running boards fail to deploy, retract immediately, or deploy randomly when parked. Motor failure on one side common from ~60k miles. GM service update: reprogram K4 Assist Step Control Module (RPO B3L/BRS). Physical motor failure: $190 OEM part, $850 dealer installed.