What it means
The transmission control module detected a performance problem with friction element B or that it did not engage as expected. The code alone does not identify the cause.
At a glance
- Usually lights the check-engine light
How it works
The transmission control module checks whether friction element B applies and produces the expected ratio when commanded. P07A4 flags poor performance or an apparent failure to engage element B; a leaking apply seal, restricted movement, or wear can cause the mismatch.
Common causes
Most likely first.
- Leaking apply seal
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
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 the freeze-frame data and review commanded gear and input/output speeds to see when element B did not produce the expected ratio.
- Check transmission fluid level and condition with the specified procedure, as low or degraded fluid can reduce the force available to apply element B.
- Inspect the transmission harness and connectors for damage or corrosion that could interrupt element B control.
- During a controlled road test, note whether shifts involving element B are delayed, missing, or accompanied by slip or shudder.
- If basic checks do not explain the fault, check hydraulic pressure and valve-body operation against the manufacturer's specification.
- If the control circuit and pressure are satisfactory, inspect element B’s apply seal and internal components for leakage, debris, or excess mechanical play.
Common fixes
- Correct the fluid level or replace degraded fluid using the specified type.
- Repair damaged wiring or restore clean, secure connector contact.
- Repair a valve-body or hydraulic fault affecting element B pressure.
- Replace a leaking apply seal or worn element B parts; clean restricted passages when found.
Can I keep driving?
Limit driving and avoid towing or hard acceleration, because element B may slip during shifts and overheat the transmission. If a shift is missing or the vehicle enters limp mode, stop safely and arrange recovery.
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.