Low, degraded or contaminated transmission fluid; Faulty shift solenoid or pressure control solenoid; Damaged wiring or poor connections at the transmission connector or control module; Faulty input or output speed sensor giving incorrect readings; Worn clutches or valve body wear causing low or erratic hydraulic pressure; Blocked transmission filter or fluid passages; Faulty transmission control module or outdated software where the manufacturer has a known fix.

P0780

Shift Error.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
80: FaultThe specific fault in that area

What it means

P0780 is the generic code for a shift error in the automatic transmission. The transmission control module has detected that a gear change did not happen as commanded, based on a mismatch between expected and actual gear ratio, input and output speed sensor readings, or shift timing. The exact way the fault is detected and the gears affected depend on the vehicle and transmission type.

Symptoms

Gearbox slow to engage or failing to change gear
Harsh, flared or slipping shifts
Gearbox stuck in one gear or in limp mode
Gearbox warning light or malfunction indicator lamp on
Engine revving without matching acceleration
Poor fuel economy or reduced performance

Possible causes

Low, degraded or contaminated transmission fluidlikely
Faulty shift solenoid or pressure control solenoidlikely
Damaged wiring or poor connections at the transmission connector or control modulepossible
Faulty input or output speed sensor giving incorrect readingspossible
Worn clutches or valve body wear causing low or erratic hydraulic pressurepossible
Blocked transmission filter or fluid passagespossible
Faulty transmission control module or outdated software where the manufacturer has a known fixrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including gear commanded, vehicle speed and fluid temperature
Check for other transmission, engine or speed sensor codes, as they may point to the root cause
Check the transmission fluid level, condition and smell using the correct procedure for the model, as some are sealed units
Inspect the transmission wiring harness and connectors for chafing, fluid ingress, corrosion and loose pins
Compare live data for input speed, output speed, commanded gear and actual gear ratio during a road test
Test the speed sensors and solenoid circuits for resistance and signal against the manufacturer's specifications
Check line pressure and solenoid operation with a pressure test where the model allows
Check for technical service bulletins and available software updates for the vehicle

How to fix

Correct the fluid level or replace the fluid and filter with the specified type if it is degraded or contaminated
Replace faulty shift or pressure control solenoids, or the valve body or solenoid pack, as the model requires
Repair or replace damaged wiring, connectors or the internal transmission harness
Replace a faulty input or output speed sensor
Overhaul or replace the transmission if there is internal clutch or hydraulic wear
Update the transmission control module software only if the manufacturer lists it as a fix for this fault

Can I keep driving?

Medium severity

The car may be driveable for a short time if it shifts normally, but continued driving with slipping or harsh shifts can cause expensive internal damage. Have it checked soon and avoid heavy loads or towing. If it is stuck in limp mode or slipping badly, stop driving and get it recovered.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.