2020 GMC Sierra 1500 Problems: 9 Known Issues

On the 2014-2023 GMC Sierra 1500, the Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) systems use special hydraulic lifters that collapse to deactivate cylinders for fuel economy. These lifters are prone to premature failure due to poor physical design and inadequate oil flow. Failures can occur as early as 4-digit mileage on newer trucks or 50,000-100,000 miles on older models. When a lifter fails, it can cause catastrophic engine damage requiring complete engine teardown.

On the 2007-2021 GMC Sierra 1500, p0016 means the crankshaft and Bank 1 intake camshaft are out of sync beyond tolerance. On the 5.3L V8 Sierra 1500 this is a signature failure because of two engine-specific problems: (1) the timing chain stretches over time — accelerated by AFM lifter debris and extended oil-change intervals — retarding cam timing until correlation exceeds threshold; and (2) the cam actuator (VVT) solenoid or phaser sticks. The AFM V8s are also known for oil consumption, and low/dirty oil starves the phasers and clogs solenoid screens, which both triggers P0016 and worsens chain wear. This is more serious than the related P0011: a severely stretched chain can jump a tooth and cause piston-to-valve contact, so continued driving is risky.

On the 2014-2023 GMC Sierra 1500, direct injection engines do not spray fuel over the intake valves like port injection systems, allowing carbon deposits from oil and blow-by gases via the PCV system to accumulate on intake valve backs and ports. Over time, this buildup restricts airflow causing performance and efficiency loss. The 5.3L and 6.2L engines with direct injection are susceptible to this issue typically after 60,000-100,000 miles.

On the 2007-2022 GMC Sierra 1500, p0011 means the Bank 1 intake camshaft is timed more advanced than the ECM commanded — the phaser is stuck/biased advanced. On the Sierra 1500 5.3L/6.2L, the dominant cause is a VVT (camshaft actuator) solenoid whose internal screen has clogged with oil sludge or AFM debris, jamming the plunger so oil pressure to the phaser can't be modulated. GM acknowledges sticking/binding solenoids in PIs such as PIP5130K and PIP5855. Low or incorrect-viscosity oil is a very common trigger, so oil condition is always checked first. Because AFM lifter wear sheds metal into the oil, that debris circulates and clogs the solenoid screens — tying P0011 directly to the trucks' oil-consumption reputation. Drivers report rough running, and in worse cases stalling when slowing to a stop.

On the 2015-2023 GMC Sierra 1500, the 8L90 8-speed and 10L80/10L90 10-speed automatic transmissions experience shuddering during light throttle acceleration, particularly at highway speeds between 35-60 mph. The issue is caused by the torque converter lock-up clutch slipping and chattering. Harsh shifts between gears, especially 1st to 2nd and 2nd to 1st, are also commonly reported.

On the 2014-2023 GMC Sierra 1500, the electronic brake control module (EBCM) experiences failures causing ABS, traction control, and stability control systems to malfunction. Issues range from warning lights illuminating to complete system failures. The 2023 models have a specific recall for software that may fail to display a warning light when brake fluid loss occurs.

On the 2014-2020 GMC Sierra 1500, the A/C compressor is prone to premature failure due to faulty welds, insufficient lubrication, or internal mechanical failure. When the compressor fails catastrophically, metal debris contaminates the entire A/C system requiring replacement of multiple components. The A/C clutch can also fail independently, preventing compressor engagement.

On the 2019-2023 GMC Sierra 1500, the infotainment system experiences intermittent complete audio loss affecting stereo, turn signals, and safety warning sounds. The audio system may randomly go to maximum volume and cannot be controlled. OTA software updates have caused additional issues including erratic blinker tones, constant reboots while driving, and frozen camera screens.

On the 2007-2023 GMC Sierra 1500, p0455 indicates a large (gross) EVAP leak — the ECM cannot pull or hold vacuum in the evaporative system at all. On the Sierra 1500 the classic causes are a completely missing/unsealed gas cap, a stuck-open or failed EVAP vent solenoid (mounted under the truck near the fuel tank/spare tire, where it's exposed to road spray, dirt, and corrosion), and a cracked or disconnected vapor/vent hose. Because the vent solenoid sits at the canister under the bed, water intrusion and corrosion cause it to stick open, which the ECM reads as a wide-open system; a tell-tale symptom is the fuel nozzle repeatedly clicking off during refueling. The filler vent hose connector fracture noted in GM literature can also escalate to P0455. Symptom-wise the driver usually sees only the CEL, sometimes a fuel smell, and no performance loss.