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Federal filingsHome›Trouble codes› U0109
Diagnostic trouble code

U0109

0 owner reports and 128 manufacturer filings across 34 model years from Ford, Genesis, Hyundai, Lincoln.

Network Generic OBD-II code 128 manufacturer filings

Where U0109 shows up

Source: NHTSA manufacturer communications and complaints
Model yearFiled underBulletinsOwner reportsParts
2019 Ford ExplorerElectrical System9—Battery →
2018 Ford ExplorerElectrical System9—Battery →
2021 Ford ExplorerElectrical System6—Battery →
2021 Ford ExpeditionElectrical System5—Battery →
2020 Ford ExpeditionElectrical System5—Battery →
2019 Ford ExpeditionPower Train5—
2018 Ford ExpeditionElectrical System5—Battery →
2020 Ford ExplorerElectrical System5—Battery →
2020 Ford F-150Electrical System5—Battery →
2020 Ford TransitElectrical System5—Battery →
2019 Ford TransitElectrical System5—Battery →
2018 Ford TransitPower Train5—
2021 Lincoln AviatorElectrical System5—Battery →
2020 Lincoln AviatorPower Train5—
2021 Lincoln NavigatorPower Train5—
2020 Lincoln NavigatorElectrical System5—Battery →
2019 Lincoln NavigatorElectrical System5—Battery →
2018 Lincoln NavigatorElectrical System5—Battery →
2022 Ford ExpeditionElectrical System4—Battery →
2022 Ford TransitElectrical System4—Battery →
2022 Lincoln AviatorElectrical System4—Battery →
2022 Lincoln NavigatorElectrical System4—Battery →
2023 Ford TransitElectrical System2—Battery →
2023 Ford Bronco SportPower Train1—
2022 Ford Bronco SportPower Train1—

Showing the 25 model years where U0109 appears most; it is on file for 34 in total.

A model year appears here because the code is named in its record, not because every one of these vehicles sets it. Counts are mentions in the federal files, not failure rates — nobody publishes the denominator.

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U0109 by make

The same record, one make at a time: the model years, bulletins and owner reports that name U0109 on that maker’s vehicles.

Ford 19Lincoln 10

What it gets filed under

Electrical System 72 Not specified 27 Power Train 24 Fuel/Propulsion System 5

128 manufacturer filings name U0109. Start with what the maker wrote down.

A code names the test that failed, not the part. A bulletin that names it is often a diagnosis someone has already written down — quote its number at the service desk.

Photo: Compagnons / Unsplash

Manufacturer filings that name it

Source: NHTSA manufacturer communications

Service bulletins and campaigns whose filed summary names U0109.

What U0109 means

Source: SAE J2012 / OBD-II

U0109 sits in the generic range of the OBD-II standard, so it means the same thing on every vehicle sold in the United States — but WhichTrim does not carry a definition for it and will not invent one. What is on this page is the record: who named it and on what.

A stored code names the test that failed, never the part that caused it. It is the starting point of a diagnosis, not its conclusion — the same code has several possible causes and the cheap one is not always right.

From here

Common questions about U0109

Source: NHTSA files and the OBD-II standard

Can I keep driving with U0109 stored?

Nobody can answer that from the code alone, and a site that does is guessing. A steady light means a fault was logged and the car should be checked soon; a flashing light means a severe misfire — slow down and get it seen as soon as possible, because severe misfire can quickly damage the catalytic converter. The safe read of this page is the mileage and the components, not permission.

Does a code mean the car is recalled?

No. Recalls are filed by campaign and matched by VIN, and none of them are triggered by a scan tool. If you want to know whether an open recall applies to one specific vehicle, check the VIN at nhtsa.gov/recalls — that is the only source that settles it.

Why do the counts here differ from other sites?

Because these are not estimates. Every number on this page is a count of documents in NHTSA's own files: manufacturer communications that name the code in their filed summary, and owner complaints that name it in the narrative. We do not model, weight or extrapolate them.

Will clearing the code fix it?

Clearing turns the light off and erases the freeze-frame data a technician would have used to work out what happened. If the condition is still there the code returns, usually within a few drive cycles, and the diagnosis now starts from less information than before.