The 2020 Sierra is the second year of the T1XX platform. The 6.2L L87 (with AFM/DFM) shows lifter collapse, the 8L90 and 10L80 transmissions shudder, and the multipro tailgate had a recall. The 3.0L Duramax diesel has separate emissions concerns.
NHTSA 19V-744 multipro tailgate recall and Siqueiros v. GM AFM/DFM lifter class action both affect 2020 Sierra. Verify completion before purchase.
Dynamic Fuel Management (next-gen AFM) collapses lifters; lifters share oil with AFM solenoids. Misfires cylinders 2/3/5/7. Repair requires removing heads. Disable DFM via tuner as preventative.
P0305 Diagnosis →TCC shudder at 30-60 mph under partial throttle. GM TSB 18-NA-355 flushes to Mobil 1 LV ATF HP. Severe cases need torque converter + pump.
P0700 Diagnosis →NHTSA 19V-744: tailgate may open inadvertently while driving. GM updates BCM software and reinforces latches free of charge.
Run an AI diagnosis →Common across GM T1XX trucks. Inlet pipe fitting leaks refrigerant. Updated part number resolves recurrence.
Run an AI diagnosis →Failed auxiliary AGM battery disables start/stop. Replace with GM-spec AGM. Some owners install a permanent disabler to prevent restart cycling.
Run an AI diagnosis →Emissions-related codes (P20EE, P2002) and CP4 fuel pump concerns. GM TSB updates address most software issues but fuel system failures can be costly.
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Multipro tailgate may open while driving due to BCM software fault. Free reflash and latch reinforcement at GM dealer.
Drain and refill transmission with Mobil 1 LV ATF HP to address torque converter shudder.
Covers 5.3L L84 and 6.2L L87 DFM lifter collapse. Eligible VINs may receive repairs and warranty extension.
If your Sierra is throwing a check engine light, these are the codes most commonly tied to the problems above. Click any code for full diagnosis steps and typical repair costs.
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Mid-pack. The DFM lifter risk and 8L90/10L80 shudder are the main concerns. Once addressed, drivetrain is durable.
Dynamic Fuel Management lifters collapse, causing misfires in cylinders 2/3/5/7. Repair runs $3-5K. Many owners disable DFM via tuner ($600) as prevention.
Yes. NHTSA 19V-744 addresses inadvertent opening of the Multipro tailgate. Free BCM update at dealer.
The 5.3L L84 (V8 with DFM) is the volume engine but shares lifter risks. 6.2L L87 has the same DFM concerns plus higher repair costs. 2.7L turbo I4 avoids DFM entirely and is becoming a popular pick. 3.0L Duramax has separate emissions concerns.
250K+ with proactive AFM/DFM disable and regular transmission service. The chassis and bottom end are durable.
2021 brought the new infotainment update and Super Cruise on Denali. Mechanically very similar. 2022 refreshed the interior.