Jeep bulletin 08-136-26
What it saysFlash: Ignition System Control Module (ISCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble… NHTSA’s full summary ↓
Jeep filed this with NHTSA as a service bulletin dated Mar 25, 2026, received Apr 1, 2026, about the engine. It names 2 model years (2023). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationFlash: Ignition System Control Module (ISCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P2C30-00 - Ignition Coil Primary Circuit Fuse A. ● P2C31-00 - Ignition Coil Primary Circuit Fuse B. ● P0300-00 - Multiple Cylinder Misfire. ● P0301-00 - Cylinder 1 Misfire Detected. ● P0302-00 - Cylinder 2 Misfire Detected. ● P0303-00 - Cylinder 3 Misfire Detected. ● P0304-00 - Cylinder 4 Misfire Detected. ● P0305-00 - Cylinder 5 Misfire Detected. ● P0306-00 - Cylinder 6 Misfire Detected. ● P0420-00 - Catalyst System Efficiency Below Threshold Bank 1. ● P0430-00 - Catalyst System Efficiency Below Threshold Bank 2. Customers may also comment on the following: ● Engine hesitates/misfires. This bulletin involves inspecting and possibly reprogramming the ISCM with the latest available software.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 08-136-26 | Service bulletin | Mar 25, 2026 | 11030416 |
What the document itself lists
Labour operations and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 18-19-33-92 | Module, Ignition System Control (ISCM) - Inspect Software Level | 0.2 hrs |
| 18-19-33-93 | Module, Ignition System Control (ISCM) - Inspect and Reprogram | 0.3 hrs |
Read by machine from the document NHTSA serves (3 pages), read Sep 29, 2026. A part number is shown only where it matches Jeep’s own catalogue shape, an operation only with its code and time, and a description only where the reader got it whole; anything it could not settle is left out, and the PDF is the record. Times are the manufacturer’s warranty allowances, not a quote. Listings and prices on eBay Motors are the seller’s.
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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.
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What owners reported
Source: NHTSA complaint databaseOwners of the 2 model years this bulletin names have filed 157 complaints with NHTSA since 2015. 67 of them name Engine — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.
The contact owns a 2023 Jeep Grand Wagoneer. The contact stated that while his wife was driving approximately 65 MPH on the highway, the vehicle lost motive power and shut off. The vehicle was later towed to the local dealer, who diagnosed that the thermostat had failed, causing the engine to overheat.
2023 Jeep Grand Wagoneer · Engine · filed with NHTSA Aug 6, 2025
Two incidences, one week apart, of car turning itself off while stopped at a red light. While stopped at the light, the a sensor flashed and the car automatically shifted from “drive” to “park.” Entire car electrical system shut off.
2023 Jeep Wagoneer · Engine · filed with NHTSA Sep 13, 2024
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
More bulletins about the engine
Source: same model, same component group59 other manufacturer communications filed against these Jeep models under the same component group (engine), newest first. The eight newest are listed; the rest are on the Jeep list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| 9100861 | Service bulletin | Aug 18, 2026 | PUMP, Auxiliary Coolant Before replacing the Auxiliary Coolant Pump, please perform the following steps: 1) Key ON/OFF and let the after-run… |
| 09-012-26 | Service bulletin | Jun 18, 2026 | Oil Pan Leak Customers may experience the following: SYMPTOM: ● 'Low Oil Level' message on in the Instrument Panel Cluster (IPC). ● Oil Leak… |
| 9100790 | Service bulletin | Mar 26, 2026 | Before replacing the water pump on 3.0L SO/HO, please follow the updated WATER PUMP INSPECTION diagnostic procedure to confirm the leak pers… |
| 9100789 | Service bulletin | Mar 26, 2026 | Before replacing the water pump on 3.0L SO/HO, please follow the updated WATER PUMP INSPECTION diagnostic procedure to confirm the leak pers… |
| 18-044-26 | Service bulletin | Mar 21, 2026 | Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle mus… |
| 18-043-26 | Service bulletin | Mar 21, 2026 | Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle mus… |
| 18-042-26 | Service bulletin | Mar 21, 2026 | Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle mus… |
| 18-041-26 | Service bulletin | Mar 21, 2026 | Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle mus… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Jeep, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Jeep 08-136-26 a recall?
No. A service bulletin 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 08-136-26 repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way.
Which vehicles does 08-136-26 cover?
The manufacturer filed it against 2 model years: 2023 Jeep Grand Wagoneer, 2023 Jeep Wagoneer. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.