The K2XX generation (2014–2018 Silverado/Sierra) brought a new platform with a cleaner exterior, improved interior, and a mix of all-new and carry-over powertrains. It introduced the EcoTec3 family of engines (4.3L, 5.3L, 6.2L) and, on later models, the new 8L90 8-speed automatic. Here are the known issues to watch for.
Engine Issues
5.3L EcoTec3 (LC9 carried over; L83 new)
- AFM/DOD lifter failure continues — same issue as GMT900; same fix: Range Technology RA003B or full AFM delete
- Oil consumption — Improved over GMT900 but still present in some early L83s; same diagnosis applies
6.2L L86 EcoTec3
- Generally more reliable than the 5.3L in terms of AFM; used in higher-duty applications
- Watch for 8L90 transmission issues (see below)
4.3L EcoTec3 V6
- Reliable engine; occasional throttle body issues similar to older V6s
Transmission Issues
8L90 8-Speed Automatic (2015+)
The new 8-speed introduced on the 6.2L K2XX is one of the most commonly complained-about transmissions on this generation.
Symptoms:
- Hunting between gears at steady speeds (constant up/down shifting at 40–55 MPH)
- Harsh 1-2 shift, especially cold
- Shudder or vibration during light throttle
- Hesitation when accelerating from a stop
Root cause: GM issued multiple TSBs for the 8L90 programming. The most effective fixes are:
- Transmission software update — check for current TCM calibration at a GM dealer
- Fluid replacement — use only Dexron HP (the 8L90’s specific fluid, not Dexron VI)
- Custom tune — a good HPTuners tune can fix most of the shift hunting with HPT MPVI4
6L80 (V6 and some V8 models)
- Same failure modes as GMT900; see 6L80 thread
Direct Injection Carbon Buildup (DI Engines)
All EcoTec3 engines use direct injection — fuel is injected directly into the cylinder, not the intake port. This means there’s no fuel washing the intake valves, leading to carbon buildup over time.
Symptoms: Rough idle, hesitation at cold start, misfires at high mileage (100K+)
Fix: Walnut blast intake valve cleaning (shop procedure) every 60K–80K miles as preventive maintenance
Electrical / Tech Issues
- MyLink touchscreen freezing or going blank — common on 2014–2015 models; often a software update or head unit replacement fixes it
- Backup camera delay — known issue on early models; software update from dealer
- OnStar/remote start not connecting — typically a modem or account subscription issue
Body & Rust
- Tailgate handle failures — The K2XX has a known issue with the exterior tailgate handle cracking or breaking; aftermarket replacements available
- Pinch weld rust — Check the bottom of the doors and body seams at 100K+