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P1738 on the 2017 Mazda CX-9

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

This code is specific to a manufacturer and is not described here. Its meaning is in the manufacturer's service information.

Bulletins for this model year that name P1738
05-002-232023-06-04. Service bulletin. 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).
05-001-21-38262021-10-02. Service bulletin. 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 on, P0780:00 - Gear shifting malfunction, P1738:00 Automatic transaxle internal malfunction. 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 changes have been implemented to reduce contamination and improve the DTC diagnostic logic. NOTE: If the vehicle also has a delayed engagement concern, this TSB is not applicable. Refer to the instructions on MGSS (SLOW ENGAGING AFTER OPERATING SELECTOR LEVER FROM N TO D POSITION [FW6A-EL/FW6AX-EL]) or (SLOW ENGAGING AFTER OPERATING SELECTOR LEVER FROM N TO D POSITION [EW6A-EL/EW6AX-EL]) for proper diagnosis and repair procedure.
05-003-20-37252020-08-04. Service bulletin. 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 changes have been implemented to reduce contamination and improve the DTC diagnostic logic.
05-004-19-34662019-05-30. Service bulletin. 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 on P0877:00 - Oil pressure switch No. 4 (oil pressure switch B) stuck on P0780:00 - Gear shifting malfunction P1738:00 - Automatic transaxle internal malfunction 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 changes have been implemented to reduce contamination and improve the DTC diagnostic logic. NOTE: If the vehicle also has a delayed engagement concern, this TSB is not applicable. Refer to the instructions on MGSS (SLOW ENGAGING AFTER OPERATING SELECTOR LEVER FROM N TO D POSITION [FW6A-EL/FW6AX-EL]) or (SLOW ENGAGING AFTER OPERATING SELECTOR LEVER FROM N TO D POSITION [EW6A-EL/EW6AX-EL]) for proper diagnosis and repair procedure.
05-004-18-34662018-05-14. Service bulletin. 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 on P0877:00 - Oil pressure switch No. 4 (oil pressure switch B) stuck on P0780:00 - Gear shifting malfunction P1738:00 Automatic transaxle internal malfunction 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 changes have been implemented to reduce contamination and improve the DTC diagnostic logic. NOTE: If the vehicle also has a delayed engagement concern, this TSB is not applicable. Refer to MGSS online for proper diagnosis and repair procedure.

5 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.