Possible Causes
WARNING: This page is about a different car, the 2002 Mazda 626 and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
Following items are possible causes for DTCs P1788 or P1789:
- Poor engine performance.
- Engine overheating.
- Low battery voltage.
- Damaged or corroded harness connection.
- Valve body malfunction.
- Transaxle overheating.