P1787
Transmission System Third or Fourth Gear Fault
P1787 is an OBD-II diagnostic trouble code meaning: Transmission System Third or Fourth Gear Fault. Common causes: shift solenoids malfunction, low or contaminated transmission fluid. Estimated repair cost: $33–278.
Symptoms
- Car won't shift into 3rd or 4th gear
- The gearbox goes into emergency mode
- Jerks when shifting gears
- Increased fuel consumption
- Check Engine light comes on
Causes
- Shift solenoids malfunction
- Low or contaminated transmission fluid
- Mechanical damage inside the automatic transmission
- Problems with the hydraulic system
- Malfunction of shaft speed sensors
How to Fix
- Check the level and condition of the transmission fluid
- Diagnose the operation of switching solenoids
- Check error codes in the TCM
- Perform a test drive with a scanner connected
- If necessary, replace faulty automatic transmission components
Related codes
Error P1787 by Vehicle Brand
FAQ
What does the P1787 code mean?
P1787 is an OBD-II diagnostic trouble code that indicates: Transmission System Third or Fourth Gear Fault
What causes a P1787 error code?
The most common causes of P1787 include: Shift solenoids malfunction; Low or contaminated transmission fluid; Mechanical damage inside the automatic transmission; Problems with the hydraulic system.
How do I fix a P1787 diagnostic trouble code?
To fix P1787: Check the level and condition of the transmission fluid. Diagnose the operation of switching solenoids. Check error codes in the TCM. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P1787?
Limited driving only, diagnose soon
How much does it cost to fix P1787?
The estimated repair cost for P1787 is $33–278. Actual cost depends on your vehicle, location, and labor rates.
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