P0759
Shift Solenoid B Intermittent.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 7
- AreaTransmission
- 59
- FaultThe specific fault in that area
What it means
P0759 is the generic code for an intermittent fault in the shift solenoid B circuit. The transmission control unit has seen the circuit's electrical signal drop out or behave erratically from time to time, rather than fail constantly. Which gears solenoid B controls differs between transmissions, so the exact effect depends on the model and gearbox.
Symptoms
- Gearbox warning light or engine management light on
- Intermittent harsh, flared or delayed gear changes
- Gearbox occasionally sticking in one gear or entering limp mode
- Occasional wrong gear selection or failure to shift up or down
- Poorer fuel economy when the fault is present
- Fault comes and goes, often with vibration, heat or damp
Possible causes
- Damaged, chafed or corroded wiring between the solenoid and the transmission control unitlikely
- Poor connection at the transmission connector or internal harness plug, including water or fluid ingresslikely
- Shift solenoid B with failing internal winding or sticking operationlikely
- Low, degraded or contaminated transmission fluid affecting solenoid operationpossible
- Low battery voltage or poor earth causing unstable supply to the control unitpossible
- Internal valve body wear or debris causing intermittent solenoid stickingpossible
- Fault within the transmission control unit itselfrare
How to diagnose
- Read all stored codes and freeze frame data to note gear, speed, temperature and load when the fault set, and check for related shift or communication codes
- Check the transmission fluid level and condition as per the manufacturer's procedure, looking for burnt smell, dark colour or debris
- Check battery condition and charging voltage, and inspect main earth connections
- Inspect the transmission harness and connectors for chafing, corrosion, bent pins, fluid contamination and loose fit
- With a scan tool that can show live data, watch solenoid status and gear commanded versus gear achieved while wiggling the harness
- Test the solenoid circuit for continuity, short to earth, short to supply and unwanted resistance, and measure solenoid winding resistance against the manufacturer's specification
- Check for technical service bulletins or calibration updates for the specific model and gearbox
- If electrical checks pass, assess the valve body and solenoid for sticking or debris, following the model-specific procedure
How to fix
- Repair or replace damaged wiring and secure the harness away from heat and rubbing points
- Clean, repair or replace corroded or loose connectors and terminals, and cure the source of any water or fluid ingress
- Replace shift solenoid B if its resistance or operation is out of specification
- Correct the transmission fluid level, or service the fluid and filter using the specified type where it is degraded
- Repair battery, charging or earth faults found during testing
- Repair or replace the valve body, or update the control unit software where a known fault is documented for that model
Can I keep driving?
Medium severity
The car can usually be driven cautiously for a short time, but erratic shifting or limp mode can stress the gearbox and become unsafe in traffic. Get it checked soon and avoid heavy loads or towing until it is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.