P3400 on Mazda vehicles
P3400 is named on 20 Mazda model years (2016–2025): 46 manufacturer filings and 1 owner report in NHTSA’s files, across CX-5, Mazda6, Mazda3, CX-30, CX-3 and 1 more.
Which Mazda model years name P3400
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2018 Mazda CX-5 | Engine | 7 | — |
| 2018 Mazda Mazda6 | Engine | 7 | — |
| 2019 Mazda CX-5 | Engine | 6 | — |
| 2019 Mazda Mazda3 | Engine | 5 | — |
| 2019 Mazda Mazda6 | Engine | 3 | — |
| 2020 Mazda CX-30 | Equipment | 2 | — |
| 2020 Mazda CX-5 | Equipment | 2 | — |
| 2020 Mazda Mazda3 | Engine | 2 | — |
| 2020 Mazda Mazda6 | Engine | 2 | — |
| 2025 Mazda CX-50 | Engine | — | 1 |
| 2021 Mazda CX-3 | Engine | 1 | — |
| 2021 Mazda CX-30 | Engine | 1 | — |
| 2021 Mazda CX-5 | Engine | 1 | — |
| 2021 Mazda Mazda3 | Engine | 1 | — |
| 2021 Mazda Mazda6 | Engine | 1 | — |
| 2020 Mazda CX-3 | Engine | 1 | — |
| 2019 Mazda CX-3 | Engine | 1 | — |
| 2018 Mazda CX-3 | Engine | 1 | — |
| 2017 Mazda CX-3 | Engine | 1 | — |
| 2016 Mazda CX-3 | Engine | 1 | — |
A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.
What Mazda owners said
Source: NHTSA complaint databaseOwners’ own words, scrubbed of anything identifying. Unverified reports filed with NHTSA — 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
Mazda filings that name P3400
Source: NHTSA manufacturer communicationsBulletins and campaigns Mazda filed with NHTSA whose summary names P3400. Quote the document number at the service desk — it is a diagnosis the maker has already written down.
- SA-041-18 Service bulletin2018-12-06 · Engine
- If you receive a customer complain of lack of power, rough idle, engine noise with stored DTC's P0340:00, P0304:00, P3400:00, P349B:00, and/or P3498:00, perform the following.
- SA-015-19 Service bulletin2019-04-08 · Engine
- If you receive a customer concern with the check engine light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.
- SA-015-19a Service bulletin2019-05-20 · Power Train
- If you receive a customer concern with the check engine light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.
- SA-022-19 Service bulletin2019-05-29 · Engine
- If you receive a customer complain of lack of power, rough idle, engine noise with stored DTC's P0340:00, P0304:00, P3400:00, P349B:00, and/or P3498:00, perform the following.
- SA-061-20 Service bulletin2020-08-05 · Engine And Engine Cooling
- If you receive a customer concern about the CHECK IN light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.
- SA-061-20a Service bulletin2020-09-10 · Equipment
- If you receive a customer concern about the CHECK IN light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, the cylinder deactivation oil control valve may be plugged with plastic debris from the oil filter wrapper. The debris may enter the center of the oil filter when poking a hole in the filter wrapper during removal, and then travel through the engine and plug the cyl
- SA-047-21 Service bulletin2021-09-16 · Engine And Engine Cooling
- If you receive a customer concern about the CHECK ENGINE light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, the cylinder deactivation oil control valve may be plugged with plastic debris from the oil filter wrapper. The debris may enter the center of the oil filter when poking a hole in the filter wrapper during removal, and then travel through the engine and plug the
What P3400 means
Source: SAE J2012 / OBD-IIP3400 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. The record above is what Mazda and its owners have filed about it; the code’s page across every make has the whole file.
Common questions
Source: NHTSA files and the OBD-II standardIs P3400 a known problem on Mazda vehicles?
It is a documented one: NHTSA's files hold 46 manufacturer filings and 1 owner report naming P3400 on 20 Mazda model years (2016–2025). Whether it is a problem on one particular car is a diagnosis, not a count — but a bulletin that names the code on your model year is the place to start.
Which Mazda models does P3400 appear on most?
2018 CX-5 (7 documents), 2018 Mazda6 (7 documents), 2019 CX-5 (6 documents).
Does P3400 on a Mazda mean it is recalled?
No. Recalls are filed by campaign and matched by VIN; no recall is triggered by a scan tool. Check the VIN at nhtsa.gov/recalls, or open the model year's page here for the campaigns filed against it.