Porsche bulletin No. 25-21
What it saysPorsche service campaign information for Workshop Campaign WMB1 - Re-Programming High-Voltage Battery Control Unit. NHTSA’s full summary ↓
Porsche filed this with NHTSA as a service bulletin dated Jul 5, 2024, received Apr 2, 2021, about the electrical system — 4 documents under this number. It names 4 model years (2016–2021). 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 communicationPorsche service campaign information for Workshop Campaign WMB1 - Re-Programming High-Voltage Battery Control Unit.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| No. 25-21 | Service bulletin | Jul 5, 2024 | 11005606 | PDF, 154 KB |
| No. 25-21 | Service bulletin | Mar 7, 2022 | 10209786 | PDF, 131 KB |
| No. 25-21 | Service bulletin | Jun 15, 2021 | 10198940 | PDF, 278 KB |
| No. 25-21 | Service bulletin | Feb 22, 2021 | 10189678 | PDF, 212 KB |
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.
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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 4 model years this bulletin names have filed 145 complaints with NHTSA since 2015. 51 of them name Electrical System — 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.
While the vehicle was charging, the protective sheath near the power outlet of the charging cable had possible electrical or fire damage. No warning lights were illuminated. Upon turning off the power and unplugging the outlet, it was determined that the plastic near the plug melted and caused the power to short.
2018 Porsche Cayenne · Electrical System · filed with NHTSA Jun 12, 2024 · ODI 11593998
The contact owns a 2017 Porsche Cayenne. The contact stated the vehicle experiencing a catastrophic powertrain and electrical failure. The vehicle experienced severe thermal overloading behind the dashboard, and the radio head unit was excessively hot causing chrome trim around the screen to melt.
2017 Porsche Cayenne · Electrical System · filed with NHTSA Oct 9, 2026 · ODI 11770216
my car had a problem in the hybrid part, before doing the diagnosis they said 3 different problems, when they gave me the diagnosis they said they didn't know what it was but that to begin with “it could be “ the components $13,000 to fix.
2016 Porsche Cayenne · Electrical System · filed with NHTSA Jun 4, 2023 · ODI 11525312
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 electrical system
Source: same model, same component group383 other manufacturer communications filed against these Porsche models under the same component group (electrical system), newest first. The eight newest are listed; the rest are on the Porsche list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| No. 35-26 | Service bulletin | Sep 29, 2026 | Technical information for a Malfunction Indicator Light Active / Warning Message All-Wheel Drive Disturbed: Fault Memory Entry “U140500 - Te… |
| No. 84-26 | Service bulletin | Sep 9, 2026 | Technical Information for Filler Flap on Vehicles with Hybrid Drive System (PHEV) Does Not Close |
| No. 81-26 | Service bulletin | Sep 8, 2026 | Technical Information for Yellow Warning Message “All-Wheel Drive System Malfunction”, “C12BEF6” and “C133700” in the All-Wheel Electronics… |
| WTK4 | Service campaign | Sep 1, 2026 | Technical Information for Campaign WTK4 – Reset Vehicle Electrical System Battery |
| No. 12-26 | Service bulletin | Sep 1, 2026 | Technical information for Damage to Nano Plug Contacts Due to Utilization of Incorrect Measuring Equipment |
| No. 2109-3 | Service bulletin | Aug 28, 2026 | Information on Advanced Technical Information for Critical 12V Li-ion Battery Recycling |
| WSL3 | Service campaign | Aug 25, 2026 | Porsche intranet posting with information on workshop campaign WSL3 - replacing electric passenger compartment heater |
| No. 2433-4 | Service bulletin | Aug 20, 2026 | Information on Advanced Technical Information for Porsche Mobile Charger NEMA Supply Cable Initialization Failure |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Porsche, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Porsche No. 25-21 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 No. 25-21 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. Every Porsche warranty extension on file lists the ones Porsche has filed.
Which vehicles does No. 25-21 cover?
The manufacturer filed it against 4 model years: 2018 Porsche Cayenne, 2017 Porsche Cayenne, 2016 Porsche Cayenne, 2021 Porsche Taycan. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.