What it means
The transmission control module detected an incorrect shift from 1st gear. The code does not specify which component caused the shift error.
At a glance
- Usually lights the check-engine light
How it works
When the transmission shifts out of 1st gear, the TCM monitors the commanded shift, gear-speed signals, and shift timing to check that the expected transition occurs. This code means the shift from 1st did not meet the module’s criteria; it does not specify whether the cause is electrical, hydraulic, or mechanical.
Common causes
Most likely first.
- Shift solenoid sticking or malfunctioning
- Low or degraded transmission fluid
- Hydraulic pressure loss or valve body fault
- Worn or damaged clutch or friction element
- Internal transmission wear or damage
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
- Record freeze-frame data and review commanded and actual gear, vehicle speed, and related transmission codes to identify the conditions when the shift from 1st failed.
- Check fluid level and condition by the manufacturer’s procedure, and inspect for leaks that could lower pressure during the initial upshift.
- Inspect transmission wiring and connectors for the shift solenoids and speed sensors, looking for damage, corrosion, or loose terminals.
- Use live data on a safe road test to see whether the TCM commands a shift out of 1st and whether speed readings show a delayed or incomplete change.
- If electrical readings are normal, test the solenoid operation and hydraulic pressure using manufacturer procedures, then check for clutch or friction-element wear.
Common fixes
- Repair fluid leaks and correct the level with the specified transmission fluid.
- Replace degraded or incorrect fluid if inspection and the service procedure indicate it is needed.
- Repair damaged shift-solenoid or speed-sensor wiring and connectors.
- Replace a solenoid confirmed faulty by circuit and operating tests.
- Repair a confirmed valve-body fault or worn clutch or friction element.
Can I keep driving?
If the vehicle hesitates badly, slips, shudders, or enters limp mode when shifting out of 1st, avoid driving it because repeated slip can worsen internal damage. If it remains controllable and shifts only mildly abnormally, drive gently and avoid heavy loads until diagnosed.
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.