Fault code P0780 – a step-by-step guide to diagnosing and fixing it

Error code P0780 is displayed and the check engine light is on - what does this mean?

DTC P0780 is recognized by the OBD system when a gearshift error is detected in the automatic transmission. This fault code indicates problems with the gearshift and can occur in both electronic and hydraulic automatic transmissions. Depending on the manufacturer, specific variants of this code can indicate different shifting problems.

What causes can this error code have?

• Defective transmission control unit (TCM)
• Worn clutches or belts in the transmission
• Low or contaminated transmission oil level
• Clogged transmission oil filter
• Defective solenoids in the transmission
• Damaged wiring to the transmission control unit
• Loose or corroded plug connections
• Worn seals and leaks
• Defective pressure or speed sensors
• Mechanical damage to gears or planetary gears

What symptoms occur in parallel with fault code P0780?

• Shifting problems: The transmission shifts jerkily or with a delay between gears
• Gear change misfires: Certain gears are not engaged or are skipped
• Loss of power: Reduced acceleration and poor driving performance
• Unusual noises: Grinding, knocking or whistling from the transmission area
• Transmission in emergency mode: The vehicle stops in a certain gear
• Increased fuel consumption: Inefficient gear changes increase fuel consumption
• Vibrations: Noticeable vibrations while driving or shifting gears

How can the problem with error code P0780 be rectified?

• Repairing error code P0780 requires a systematic diagnosis of the transmission components.
• Change the transmission oil and filter, check the oil level and quality and replace contaminated or burnt fluid with fresh ATF
• Read out and reprogram the transmission control unit or, in the event of irreparable damage, have the TCM completely replaced
• Identify defective solenoid coils in the transmission and replace individually or as a complete set, including seals and wiring
• Check electrical cables and plug connections to the transmission, repair damaged cables and clean or replace corroded contacts
• Dismantle the gearbox and replace worn clutches, belts or mechanical components, which requires a general overhaul
• Test pressure and speed sensors in the transmission and replace defective sensors with new original parts