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Diagnostic trouble code

P3400

2 owner reports and 88 manufacturer filings across 32 model years from Acura, Chevrolet, Honda, Mazda.

PowertrainManufacturer-specific88 manufacturer filings2 owner reports

Where P3400 shows up

Source: NHTSA manufacturer communications and complaints
Model yearFiled underBulletinsOwner reports
2018 Mazda CX-5Engine7
2018 Mazda Mazda6Engine7
2019 Mazda CX-5Engine6
2019 Mazda Mazda3Engine5
2017 Acura MDXEngine And Engine Cooling4
2017 Acura RDXEngine And Engine Cooling4
2017 Acura RLXEngine And Engine Cooling4
2017 Acura TLXEngine And Engine Cooling4
2017 Chevrolet CorvetteElectrical System4
2016 Chevrolet CorvetteElectrical System4
2017 Honda OdysseyEngine And Engine Cooling4
2017 Honda PilotEngine And Engine Cooling4
2017 Honda RidgelineEngine And Engine Cooling4
2017 Chevrolet CamaroEquipment3
2016 Chevrolet CamaroEquipment3
2019 Mazda Mazda6Engine3
2020 Mazda CX-30Equipment2
2020 Mazda CX-5Equipment2
2020 Mazda Mazda3Equipment2
2020 Mazda Mazda6Equipment2
2016 Honda OdysseyEngine1
2021 Mazda CX-3Engine And Engine Cooling1
2020 Mazda CX-3Engine And Engine Cooling1
2019 Mazda CX-3Engine And Engine Cooling1
2018 Mazda CX-3Engine And Engine Cooling1
2017 Mazda CX-3Engine And Engine Cooling1
2016 Mazda CX-3Engine And Engine Cooling1
2021 Mazda CX-30Engine And Engine Cooling1
2021 Mazda CX-5Engine And Engine Cooling1
2025 Mazda CX-50Engine1
2021 Mazda Mazda3Engine And Engine Cooling1
2021 Mazda Mazda6Engine And Engine Cooling1

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.

What it gets filed under

Engine And Engine Cooling 43Equipment 16Engine 14Electrical System 9Equipment Adaptive/Mobility 4Power Train 2
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What owners said

Source: NHTSA complaint database

Owners’ own words, one per nameplate, scrubbed of anything identifying. These are unverified reports filed with NHTSA — they are what was said, not a finding that it was true.

Took it to the dealer and the code was a p3400 code, cylinder deactivation fault
2025 Mazda CX-50Feb 7, 2025NHTSA owner report
Now getting engine cod p3400 vps bank 1 within 1200 miles of the first issue
2016 Honda OdysseyJan 22, 2023NHTSA owner report

Manufacturer filings that name it

Source: NHTSA manufacturer communications

Service bulletins and campaigns whose filed summary names P3400. Quoting the document number at a service desk is often the fastest route to a diagnosis someone has already written down.

What P3400 means

Source: SAE J2012 / OBD-II

P3400 is a manufacturer-specific code: the second character is a 3, which under the OBD-II standard hands the definition to whoever built the vehicle. The same code can mean one thing on a Ford and something unrelated on a Hyundai. Any site that prints a single definition for it is guessing.

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.

Common questions about P3400

Source: NHTSA files and the OBD-II standard

Why does this page not define P3400?

Because it cannot be defined honestly. The second character of a trouble code says who owns its meaning, and a 1 or a 3 hands that to the manufacturer. Sites that print one definition for a manufacturer-specific code are showing you one automaker's meaning and hoping it is yours.

Can I keep driving with P3400 stored?

Nobody can answer that from the code alone, and a site that does is guessing. A steady light generally means the fault was logged and the vehicle is in a reduced-risk mode; a flashing light means stop soon, because a misfiring engine can destroy a catalytic converter in minutes. 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.