2020 GMC Yukon Problems: 8 Known Issues

On the 2007-2020 GMC Yukon, the GMC Yukon 5.3L (L83, LC9, LMG) and 6.2L (L94, L86) V8 engines use Active Fuel Management (AFM) cylinder deactivation. The special collapsible AFM lifters on cylinders 1, 4, 6, and 7 fail prematurely, causing misfires, engine ticking, rough idle, and potential catastrophic damage. This is the single most reported mechanical failure on GMT900 (2007-2014) and K2XX (2015-2020) Yukon models. GM issued TSB 18-NA-077 acknowledging the issue. Yukon models used as daily drivers with lots of highway cruising (where AFM activates most) are most susceptible. The VLOM (Valve Lifter Oil Manifold) must also be replaced as it controls oil flow to AFM lifters.

On the 2015-2020 GMC Yukon, the 8L90 8-speed automatic transmission in 2015-2020 Yukon and Yukon XL suffers from widespread torque converter lock-up clutch shudder at light throttle between 25-50 mph. The clutch friction material degrades and contaminates the transmission fluid, causing the shudder to worsen over time. GM extended warranty coverage to 6 years/100,000 miles under Customer Satisfaction Program 18302. The fluid fix (Mobil 1 Synthetic LV ATF HP, GM 19417577) resolves early-stage cases; advanced cases require torque converter replacement. This is the same issue affecting all K2XX platform full-size GM SUVs and trucks.

On the 2015-2024 GMC Yukon All engines with Integrated Trailer Brake Control (RPO JL1), the Yukon's Integrated Trailer Brake Control system (RPO JL1) is considerably more sensitive to connection quality than the aftermarket brake controllers it replaced. Rather than simply switching current to the trailer when the pedal is pressed, the Trailer Brake Power Control Module (K133) sends a continuous low-level test pulse down trailer brake output circuit 47 — pin 2, the blue wire on the 7-way. The Chassis Control Module (K38), Chassis Control Module Auxiliary (K38A) or Brake System Control Module (K160), depending on model year, reads the response of that pulse to determine whether a trailer is attached, what kind of brakes it has, and whether the circuit is healthy. Because the module is effectively monitoring circuit integrity continuously, ordinary trailer-grade wiring faults that an older controller would have tolerated now register as hard faults. GM's PIT5509-series bulletins spell out the exact mapping between what the driver sees and what the circuit is doing: a 'Check Trailer Wiring' message with no DTC means an open and/or high resistance occurred in circuit 47 during that ignition cycle; a 'Check Trailer Wiring' message with DTC C1114 and no Service Trailer Brake message means a short to ground on circuit 47; and a 'Service Trailer Brake System' message with C1114 means a short to power on circuit 47 or a poor trailer ground. That last combination is the one Yukon owners hit most, and it is usually caused on the trailer side rather than the vehicle side. The usual culprits are a poor or loose connection at the 7-way, a corroded or water-intruded connector on either the Yukon's hitch receiver or the trailer plug, a trailer ground wire bolted to a painted or rusted frame rail instead of bare metal, chafed brake wiring rubbing through against an axle or frame crossmember, or excessive harness length that lets the plug work loose while driving. Salt-belt vehicles and trailers that get dunked at boat ramps are heavily overrepresented. Because a marginal ground can hold up under light braking and fail under load, the fault often shows up mid-trip on a grade, exactly when the trailer brakes matter most. GM is blunt about where the problem usually lies: it notes that most trailers with these wiring issues do not have high standards for wiring, connections, splices and routing compared with automotive practice, which is precisely why a module that continuously monitors circuit integrity trips on them.

On the 2015-2025 GMC Yukon, the power retractable running boards available on 2015+ Yukon and Yukon XL are a common failure point. The electric motors and gearboxes corrode and seize, especially in salt-belt states. Boards get stuck in the out position (creating a road-clearance hazard and trip risk) or refuse to extend. The wiring harness connections at the running board motors corrode. GM has released multiple updated motor designs, but corrosion in the mechanical linkage pins also causes binding. Repair cost is $800-2,000 per side if both motors fail.

On the 2015-2020 GMC Yukon, the 8-inch MyLink/IntelliLink infotainment touchscreen (RPO IO5/IO6) develops ghost touches where it presses buttons by itself, dead zones that stop responding, and delamination/bubbling where the digitizer separates from the LCD. Because so many K2XX Yukons share this radio, it is one of the most common infotainment failures on the platform, disabling climate, backup-camera overlays, and audio controls that are routed through the screen.

On the 2007-2020 GMC Yukon, yukon and Yukon XL models equipped with Autoride (RPO Z55) or electronic suspension feature rear air springs and a compressor that commonly fail between 80,000-130,000 miles. The air spring bags crack from age and temperature cycling, causing the rear of the vehicle to sag overnight. The compressor burns out from running continuously to compensate for air spring leaks. Replacing OEM components and having them fail again is common — many owners convert to passive coil springs. Same system as Chevy Tahoe/Suburban and Escalade.

On the 2007-2020 GMC Yukon, the mechanical (belt-driven) water pump develops internal bearing and seal wear with age and mileage, then leaks coolant from the weep hole at the front-center of the engine. Left unaddressed the pump can drip DEXCOOL onto the ground, run the cooling system low, and cause overheating. It is a common wear item on the Gen IV/V small-block V8s used across the GMT900 and K2XX Yukon and typically shows up beyond ~90,000-120,000 miles.

On the 2007-2020 GMC Yukon, on Autotrac electronic-shift 4WD Yukons the transfer-case encoder motor and its position sensor/selector switch fail, so the module can no longer confirm the range. The dash 4WD buttons flash, the truck won't shift between 2HI/4HI/4LO or gets stuck in one range, the Service 4WD light comes on, and codes such as C038D 'Range Actuator Position Not Learned' are stored. Worn encoder-motor contacts and corroded connector pins are typical causes.