Jeep warranty extension 66D Combo Rev1
Jeep filed this with NHTSA as a warranty extension dated Jul 27, 2026, received Sep 3, 2026, about the engine. It names 2 model years (2026–2027). A warranty extension is not a safety recall — there is no NHTSA campaign number and no federal requirement — but it is usually work the manufacturer pays for on the vehicles it names; the dealer checks the VIN against the manufacturer’s list.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationCUSTOMER SATISFACTION NOTIFICATION NORTH AMERICA Spark Plugs Reference: 66D 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.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 66D Combo Rev1 | Warranty extension | Jul 27, 2026 | 11036780 | not yet checked |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themA vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
Common questions
Source: NHTSA, 49 CFR 579.5Is Jeep 66D Combo Rev1 a recall?
No. A warranty extension is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the 66D Combo Rev1 repair free?
A warranty extension is usually paid by the manufacturer on the vehicles it names, within the terms and time limit the document sets; the dealer checks the VIN against the manufacturer’s list.
Which vehicles does 66D Combo Rev1 cover?
The manufacturer filed it against 2 model years: 2027 Jeep Grand Cherokee, 2026 Jeep Grand Cherokee. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.