Jeep Grand Cherokee 2026 — service campaign
Bulletin 66D Dealer · NHTSA communication 11035327 · issued Jul 22, 2026
Service campaign
communication type
Engine
component
2026
model years
3
vehicle entries
Official summary
Spark Plugs The spark plugs insulator on approximately 48,000 of the above vehicles may break due to excessive cylinder pressure. This pressure can cause the spark plug's ceramic insulator to crack, leading to a rough running engine. If this issue is not resolved promptly, the broken fragments can fall into the cylinder and cause internal engine damage.
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.