Kia bulletin PI2104
What it saysPRODUCT IMPROVEMENT CAMPAIGN: THETA 2.4L MPI - KNOCK SENSOR DETECTION SYSTEM (KSDS) ECU LOGIC IMPROVEMENT (PI2104) - This bulletin provides information related to a software update to the Engine Control Unit (ECU)… NHTSA’s full summary ↓
Kia filed this with NHTSA as a service bulletin dated Mar 18, 2026, received Aug 2, 2021, about the engine — 7 documents under this number: PI2104_OWNR_501, PI2104_OWNR_401, PI2104_OWNR_301, PI2104_OWNR_201 and 3 more. It names 1 model year (2016). 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 communicationWhat it applies to, as the document itself states it — the build window in the manufacturer’s own words, read by machine from the PDF NHTSA serves. The build date is on the certification label in the driver’s door jamb; the dealer settles a borderline vehicle by its VIN.
PRODUCT IMPROVEMENT CAMPAIGN: THETA 2.4L MPI - KNOCK SENSOR DETECTION SYSTEM (KSDS) ECU LOGIC IMPROVEMENT (PI2104) - This bulletin provides information related to a software update to the Engine Control Unit (ECU) to install the Knock Sensor Detection System (KSDS), in order to protect the engine from excessive connecting rod bearing damage. This update is for certain 2014-2016MY Optima Hybrid (TF HEV) vehicles equipped with Theta 2.4L MPI engines, produced from December 11, 2013 through July 22, 2015.
Trouble codes it names: P1326 all 1 read from the document itself; NHTSA’s summary names none
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| PI2104_OWNR_501 | Other | Mar 18, 2026 | 11030342 | PDF, 194 KB |
| PI2104_OWNR_401 | Other | Jul 15, 2025 | 11020817 | PDF, 132 KB |
| PI2104_OWNR_301 | Other | Nov 20, 2024 | 11010705 | PDF, 152 KB |
| PI2104_OWNR_201 | Service bulletin | Mar 19, 2024 | 10251445 | PDF, 144 KB |
| PI2104_OWNR | Service bulletin | Jul 13, 2021 | 10199207 | PDF, 185 KB |
| PI2104_TSB | Service bulletin | Jul 8, 2021 | 10199208 | PDF, 634 KB |
| PI2104_QA | Service bulletin | Jul 8, 2021 | 10199206 | PDF, 110 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.
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 1 model year this bulletin names have filed 764 complaints with NHTSA since 2015. 558 of them name Engine, 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.
On the 2016 Kia Optima, the 145 owners who gave an odometer reading for Engine reported it at a median of 91,176 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
For the 2nd year, my Kia would not start in 32 degree weather in big bear, ca. This is an annual trip & took my Kia. The lights, radio all turn on but the engine will not start. I have to wait until noon for the sun to warm up the car & then it's back to normal.
2016 Kia Optima · Engine · filed with NHTSA Mar 4, 2019 · ODI 11183935
Dear NHTSA, I am writing to formally report a serious safety incident involving my 2016 Kia Optima Hybrid, which caught fire and was completely destroyed on October 5, 2025.
2016 Kia Optima · Electrical System · filed with NHTSA Oct 21, 2025 · ODI 11694645
In depth: 2016 Kia Optima engine problems → · 2016 Kia Optima electrical problems →
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 group7 other manufacturer communications filed against the Kia Optima under the same component group (engine), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| PI2108 | Service bulletin | Apr 15, 2026 | PRODUCT IMPROVEMENT CAMPAIGN NU 2.0L GDI - KNOCK SENSOR DETECTION SYSTEM (KSDS) ECU LOGIC IMPROVEMENT (PI2108) - This bulletin provides info… |
| SC340 | Emissions | Apr 4, 2026 | VOLUNTARY EMISSIONS SERVICE CAMPAIGN: THETA II 2.4L GDI EMISSIONS: ECM LOGIC IMPROVEMENT (SC340 REVISION 5) - This bulletin has been revised… |
| TSB_ENG222_R8 | Service bulletin | Apr 3, 2025 | TECHNICAL SERVICE BULLETIN: EXCESSIVE OIL CONSUMPTION NU/GAMMA/THETA/KAPPA ENGINES - This bulletin has been revised to include additional in… |
| TSB_ENG222_R7 | Service bulletin | Feb 28, 2025 | TECHNICAL SERVICE BULLETIN: EXCESSIVE OIL CONSUMPTION NU/GAMMA/THETA/KAPPA ENGINES - This bulletin has been revised to include additional in… |
| PI2108Y/Z | Service bulletin | Nov 8, 2024 | TECHNICAL SERVICE BULLETIN: PRODUCT IMPROVEMENT CAMPAIGN: SUBSEQUENT REPAIR ACTION: ENGINE REPLACEMENT INSTRUCTIONS FOR DTC P1326… |
| PI1802YZ_TSB_R5 | Service bulletin | Mar 22, 2024 | PRODUCT IMPROVEMENT CAMPAIGN: ENGINE REPLACEMENT INSTRUCTIONS FOR DTC P1326 (PI1802Y/Z) - This bulletin has been revised to include additio… |
| PI1805YZ | Service bulletin | Jan 12, 2024 | TECHNICAL SERVICE BULLETIN: PRODUCT IMPROVEMENT (PI1805Y/Z) - This bulletin provides information related to the Technical Service Bulletin p… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Kia, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Kia PI2104 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 PI2104 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 Kia warranty extension on file lists the ones Kia has filed.
Which vehicles does PI2104 cover?
The manufacturer filed it against 1 model year: 2016 Kia Optima. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone. The document itself sets the build window: 2014-2016MY Optima Hybrid (TF HEV): built 11 Dec 2013 – 22 Jul 2015; Optima Hybrid (TF HEV): built 11 Dec 2013 – 22 Jul 2015 — the build date is on the certification label in the driver’s door jamb.