What it means
The transmission control module monitors the Shift Solenoid H circuit for intermittent operation. It sets this code when the circuit signal or solenoid response drops out or becomes erratic during operation.
At a glance
- Usually lights the check-engine light
How it works
Shift solenoid H controls a hydraulic shift function through an electrical command from the transmission control module. This code sets when the H circuit or solenoid response drops out or becomes erratic during operation, rather than remaining consistently faulty.
Common causes
Most likely first.
- Loose connector at the transmission
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and note the speed, temperature, and gear when the fault occurred, then check whether it returns under similar conditions.
- Inspect the transmission connector for a loose fit, corrosion, fluid, or damaged terminals that could lose contact with vibration.
- Trace the solenoid H harness and look for rubbing, tension, or contact with a vibrating or hot component.
- Monitor solenoid H command and circuit status with a scan tool while gently moving the accessible harness and connector to reproduce a dropout.
- If the wiring remains stable, test solenoid H and its circuit for intermittent continuity or response under the manufacturer’s diagnostic procedure.
Common fixes
- Secure the transmission connector and repair loose or corroded terminals.
- Repair or reroute harness sections that rub or vibrate against nearby parts.
- Replace a damaged connector or wiring section causing intermittent contact.
- Replace shift solenoid H if testing confirms its operation drops out intermittently.
Can I keep driving?
Avoid long trips or heavy loads until the intermittent fault is found, since a sudden shift disruption can affect acceleration and may lead to transmission overheating if slipping occurs. Stop driving if shifts become unpredictable.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.