P1738
0 owner reports and 128 manufacturer filings across 34 model years from Mazda.
Where P1738 shows up
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports | Parts |
|---|---|---|---|---|
| 2016 Mazda CX-5 | Power Train | 9 | — | |
| 2016 Mazda Mazda3 | Power Train | 9 | — | |
| 2016 Mazda Mazda6 | Power Train | 9 | — | |
| 2016 Mazda CX-3 | Engine | 8 | — | |
| 2018 Mazda CX-3 | Power Train | 5 | — | |
| 2017 Mazda CX-3 | Power Train | 5 | — | |
| 2018 Mazda CX-5 | Power Train | 5 | — | |
| 2017 Mazda CX-5 | Power Train | 5 | — | |
| 2018 Mazda CX-9 | Power Train | 5 | — | |
| 2017 Mazda CX-9 | Power Train | 5 | — | |
| 2016 Mazda CX-9 | Power Train | 5 | — | |
| 2018 Mazda Mazda3 | Power Train | 5 | — | |
| 2017 Mazda Mazda3 | Power Train | 5 | — | |
| 2018 Mazda Mazda6 | Power Train | 5 | — | |
| 2017 Mazda Mazda6 | Power Train | 5 | — | |
| 2019 Mazda CX-3 | Power Train | 4 | — | |
| 2019 Mazda CX-5 | Power Train | 4 | — | |
| 2019 Mazda CX-9 | Power Train | 4 | — | |
| 2019 Mazda Mazda6 | Power Train | 4 | — | |
| 2021 Mazda CX-5 | Power Train | 2 | — | |
| 2020 Mazda CX-5 | Power Train | 2 | — | |
| 2021 Mazda CX-9 | Power Train | 2 | — | |
| 2020 Mazda CX-9 | Power Train | 2 | — | |
| 2016 Mazda MX-5 | Engine | 2 | — | |
| 2021 Mazda Mazda6 | Power Train | 2 | — |
Showing the 25 model years where P1738 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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P1738 by make
The same record, one make at a time: the model years, bulletins and owner reports that name P1738 on that maker’s vehicles.
What it gets filed under
128 manufacturer filings name P1738. 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.
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names P1738.
- 05-001-25a Service bulletin2025-11-23 · Power Train
- Some customers may see the A/T warning light on during (or immediately after) engine start-up with DTCs P073D:00-TCM / P1738:00-TCM stored. P073D:00-TCM: Turbine/input shaft speed sensor: Sensor output range malfunction P1738:00-TCM: Automatic transaxle internal malfunction This concern is caused by improper TCM logic. To eliminate this concern, the TCM control software has been modified to change
- 05-002-23 Service bulletin2023-05-17 · Power Train — Automatic Transmission — Control Module (Tcm/Pcm/Tecm)
- Some vehicles may experience the check engine light and automatic transaxle warning light ON with one or more of these DTCs stored in the TCM memory (P0842, P0847, P0872, P0877, P0780, P1738).
- 05-001-21-3826 Service bulletin2021-09-03 · Power Train
- Some vehicles may experience the check engine light and automatic transaxle warning light ON with one or more of these DTCs stored in the TCM memory (P0842, P0847, P0872, P0877, P0780, P1738). P0842:00 - Oil pressure switch No. 1 (oil pressure switch B) stuck on, P0847:00 - Oil pressure switch No. 2 (oil pressure switch A) stuck on, P0872:00 - Oil pressure switch No. 3 (oil pressure switch A) stuc
- 05-003-20-3725 Service bulletin2020-07-09 · Engine
- Some vehicles may experience the check engine light and automatic transaxle warning light ON with one or more of these DTCs stored in the TCM memory (P0842, P0847, P0872, P0877, P0780, P1738). This is caused by the oil pressure switch A and/or B at the control valve body temporarily or permanently getting stuck due to contamination entering the passage. To correct the problem, some mass production
- 05-004-19-3466 Service bulletin2019-05-20 · Power Train
- Some vehicles may experience the check engine light and automatic transaxle warning light ON with one or more of these DTCs stored in the TCM memory (P0842, P0847, P0872, P0877, P0780, P1738). P0842:00 - Oil pressure switch No. 1 (oil pressure switch B) stuck on P0847:00 - Oil pressure switch No. 2 (oil pressure switch A) stuck on P0872:00 - Oil pressure switch No. 3 (oil pressure switch A) stu
- 05-004-18-3466 Service bulletin2018-04-16 · Engine And Engine Cooling
- Some vehicles may experience the check engine light and automatic transaxle warning light ON with one or more of these DTCs stored in the TCM memory (P0842, P0847, P0872, P0877, P0780, P1738). P0842:00 - Oil pressure switch No. 1 (oil pressure switch B) stuck on P0847:00 - Oil pressure switch No. 2 (oil pressure switch A) stuck on P0872:00 - Oil pressure switch No. 3 (oil pressure switch A) stuck
What P1738 means
Source: SAE J2012 / OBD-IIP1738 is a manufacturer-specific code: the second character is a 1, 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 P1738
Source: NHTSA files and the OBD-II standardWhy does this page not define P1738?
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 P1738 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.