What it means
While in 7th gear, the ratio measured between input shaft speed and output shaft speed does not match the calibrated value for that gear. Either a clutch or band is slipping, the wrong gear actually engaged, or speed sensor data is wrong.
At a glance
- Usually lights the check-engine light
How it works
The transmission control module uses input and output speed data to check whether the transmission is operating in the expected sixth-gear ratio. This code sets when the measured ratio does not match the calibrated sixth-gear ratio, which can result from slipping, the wrong gear engaging, or inaccurate speed data.
Common causes
Most likely first.
- Slipping clutch in 7th gear element
- Wrong shift solenoid pattern engaging the wrong gear
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 review commanded gear, actual gear, and input and output speeds to confirm the fault occurred while sixth gear was expected.
- Check transmission fluid level and condition using the manufacturer’s procedure, since low or degraded fluid can contribute to clutch slip.
- Inspect the input and output speed sensor wiring and connectors for damage, contamination, or loose connections that could produce incorrect ratio data.
- Use a scan tool to compare commanded gear with actual gear and observe input and output speeds during a controlled road test, if safe.
- If speed readings are plausible but sixth-gear ratio remains incorrect, diagnose the shift solenoid pattern and inspect the clutch or band elements used for sixth gear.
Common fixes
- Correct the transmission fluid level or service the fluid as specified.
- Repair damaged speed sensor wiring or secure a poor connector.
- Replace a confirmed faulty input or output speed sensor.
- Repair a confirmed shift solenoid or hydraulic control fault that prevents sixth gear from engaging correctly.
- Repair the slipping clutch or band if internal transmission testing confirms wear or damage.
Can I keep driving?
Avoid high speeds, towing, and hard acceleration if the transmission slips or cannot hold sixth gear; continued slip can quickly overheat and damage internal parts. Stop if the vehicle loses drive or shifts unpredictably.
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.