Error code

OBD2 P0784

OBD2P0784
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

4-5 Shift.

Severity

moderateCan drive but may experience shifting issues. Addressing the issue is recommended.

Summary

P0784 indicates a malfunction in the hydraulic or electrical circuit controlling gear shifts between fourth and fifth gears in an automatic transmission.

Symptoms

  • No symptoms other than a stored trouble code and possibly an illuminated CHECK ENGINE light
  • Transmission slippage, failure to engage any gear, harsh shifting, overheating, increased fuel consumption, entering limp mode

Common Causes

  • Low transmission fluid levels or degraded fluid
  • Incorrect or unsuitable transmission fluid
  • Blocked internal fluid passages
  • Faulty wiring and connectors
  • Defective shift solenoids
  • Mechanical failures inside the transmission
  • TCM/PCM failure (rare)

Diagnosis

  1. Extract and record all fault codes and freeze frame data
  2. Inspect wiring for continuity, ground, and resistance
  3. Check transmission fluid level, condition, and smell
  4. Replace transmission fluid if necessary
  5. Remove oil pan to check for debris or mechanical issues
  6. Inspect internal wiring and connectors
  7. Test shift solenoid manually with a code reader
  8. Check transmission operating pressure

Fixes

  • Replace faulty shift solenoids, repair wiring/connectors, replace transmission fluid, check for debris in oil pan

FAQ

What should I do if the code persists after replacing the fluid and checking the solenoid?

If the issue continues, it may indicate a mechanical failure or low transmission pressure. Consult a professional for further diagnosis.

Can P0784 be caused by electrical issues?

Yes, faulty wiring and connectors can cause this code to set.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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