OBD Guide

P1786

Transmission System Second or Third Gear Fault

P1786 is an OBD-II diagnostic trouble code meaning: Transmission System Second or Third Gear Fault. Common causes: low or contaminated transmission fluid, shift solenoids malfunction. Estimated repair cost: $22–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$22–167 (est.)

Symptoms

  • Incorrect gear shifting
  • Delays when switching to second or third gear
  • Power dips
  • Increased noise during gearbox operation
  • Switching to emergency mode

Causes

  • Low or contaminated transmission fluid
  • Shift solenoids malfunction
  • Problems with the hydraulic block
  • Wear of mechanical components of the gearbox
  • Problems with electronic control (TCM)

How to Fix

  1. Check the level and condition of the transmission fluid
  2. Diagnose the gearshift solenoids
  3. Check the hydraulic unit for leaks and damage
  4. Inspect the mechanical components of the transmission
  5. Check electrical connections and wiring harness

Related codes

Error P1786 by Vehicle Brand

FAQ

What does the P1786 code mean?

P1786 is an OBD-II diagnostic trouble code that indicates: Transmission System Second or Third Gear Fault

What causes a P1786 error code?

The most common causes of P1786 include: Low or contaminated transmission fluid; Shift solenoids malfunction; Problems with the hydraulic block; Wear of mechanical components of the gearbox.

How do I fix a P1786 diagnostic trouble code?

To fix P1786: Check the level and condition of the transmission fluid. Diagnose the gearshift solenoids. Check the hydraulic unit for leaks and damage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1786?

Limited driving only, diagnose soon

How much does it cost to fix P1786?

The estimated repair cost for P1786 is $22–167. Actual cost depends on your vehicle, location, and labor rates.

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