2018 GMC Sierra 2500HD: Engine complaints
Owner-reported issue (NHTSA complaints, not a recall)
Symptoms
NHTSA has 8 owner complaints for the 2018 GMC Sierra 2500HD that list the engine component. Complaints are individual owner reports, not verified defects.
Examples:
- NHTSA complaint ODI #11736800 (filed 05/09/2026): “Gm duramax l5p diesel engine electrical connector for #4 fuel injector. this failure caused the diesel exhaust brake, which controls downhill speed, to disengage, extreme shaking of the vehicle, emissions system warning and speed limiting. this occurred while descending a steep grade while towing…”
- NHTSA complaint ODI #11553906 (filed 11/07/2023): “Metal in the fuel filter and throughout the fuel system, 38 codes on the computer just in 2 weeks after a full service again at the dealer. all service has been preformed at a gmc dealer since truck was serviced. 1. p026d - fuel injection quantity “a” higher then expected 2. p06cc - cylinder 8 in…”
- NHTSA complaint ODI #11553304 (filed 11/02/2023): “Constant issues with glow plug failures, fuel rail failure, fuel pressure failure. truck has been in the gmc service regarding these issues constantly for the last year with a total of five repairs and replacement of glow plugs with releaning learning new plugs and now the 6th return to the shop the…”
Likely causes
These complaints do not establish a single root cause; read the examples above and get a diagnosis.
Fix, in plain English
No single fix is established by these reports. Check your VIN for open recalls at nhtsa.gov/recalls, ask a dealer about technical service bulletins (TSBs) or extended warranty coverage, then have the system diagnosed.
DIY difficulty: Pro
Internal engine work (lifters, oil consumption, fuel dilution diagnosis) requires engine teardown or dealer software/tests. (Our assessment.)
Cost
No sourced cost range for this issue. Get a written quote after diagnosis.
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