Intermittent wiring fault or poor connection at the solenoid or transmission connector (chafing, corrosion, loose pin); Internal transmission harness fault or damaged connector; Failing shift solenoid C with intermittent coil resistance or sticking; Low, contaminated or degraded transmission fluid affecting solenoid operation; Debris or valve body wear causing the solenoid or valve to stick intermittently; Low battery voltage or poor earth or supply to the transmission control unit; Faulty transmission control unit or outdated software where a known fault exists for that model.

P0764

Shift Solenoid C Intermittent.

Generic
Powertrain
Generic code
Medium severity

How this code is built

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

What it means

P0764 is the generic code for an intermittent fault in the shift solenoid C circuit or its operation. The transmission control unit saw the solenoid's electrical circuit or its commanded and actual gear behaviour drop in and out of range, rather than fail permanently. Which gears solenoid C controls depends on the make, model and transmission, so the exact effect varies.

Symptoms

Harsh or flared gear shifts that come and go
Occasional failure to select a particular gear
Transmission going into limp mode (fixed gear) intermittently
Gearbox warning light or malfunction indicator lamp on
Incorrect gear ratio or slipping at times
Poor fuel economy or erratic shift timing

Possible causes

Intermittent wiring fault or poor connection at the solenoid or transmission connector (chafing, corrosion, loose pin)likely
Internal transmission harness fault or damaged connectorlikely
Failing shift solenoid C with intermittent coil resistance or stickinglikely
Low, contaminated or degraded transmission fluid affecting solenoid operationpossible
Debris or valve body wear causing the solenoid or valve to stick intermittentlypossible
Low battery voltage or poor earth or supply to the transmission control unitpossible
Faulty transmission control unit or outdated software where a known fault exists for that modelrare

How to diagnose

Read all stored and pending codes and freeze frame data to see when the fault set (speed, gear, fluid temperature, load)
Check the transmission fluid level, condition and smell, following the manufacturer's procedure for that model
Inspect the wiring and connectors to the transmission for chafing, corrosion, fluid ingress and bent or loose pins
Check battery condition and charging voltage, and the control unit supply and earth connections
Wiggle-test the harness with live data or a monitoring tool while watching for the fault returning or the solenoid command dropping out
Measure the solenoid C coil resistance and circuit continuity against the manufacturer's specification for that transmission
Check for technical service bulletins or software updates relating to this code for the specific model
If the fluid is contaminated, inspect the pan and filter for debris before condemning parts

How to fix

Repair or replace damaged wiring, terminals or connectors in the solenoid circuit
Replace the internal transmission harness or connector if it is faulty
Replace shift solenoid C, or the solenoid pack where it is supplied as an assembly
Correct the fluid level or replace degraded fluid and filter with the specified type
Clean or repair the valve body if debris or wear is found
Update the control unit software only if an applicable update exists for a known fault, or repair or replace the unit if confirmed faulty

Can I keep driving?

Medium severity

The car can usually be driven short distances carefully, but intermittent harsh shifts or limp mode can stress the transmission, so get it checked soon. Stop driving if it will not select gears reliably or slips badly.

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