What it means
The electric/auxiliary transmission fluid pump control valve circuit is not performing within the expected range.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The electric or auxiliary transmission pump control valve adjusts hydraulic flow or pressure in response to module commands. The module monitors how the valve circuit responds and sets P27E4 when its electrical or operating behavior falls outside the expected range, which may reflect a coil, connection, or circuit problem.
Common causes
Most likely first.
- Control-valve coil resistance out of specification
- High-resistance connection in wiring or connector
- Control-valve circuit fault
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
- Capture freeze-frame data and review live data for pump control-valve command and response, along with pump pressure and related transmission faults.
- Inspect the control-valve connector and harness for corrosion, loose pins, fluid contamination, or damage that could cause a resistive connection.
- Check the control-valve coil resistance and compare it with the manufacturer's specification.
- Check wiring continuity and voltage drop through the valve circuit while following the manufacturer's procedure to find excessive resistance or an unstable connection.
- If the circuit tests correctly, evaluate valve operation and the module's commanded output using the manufacturer's diagnostic procedure.
Common fixes
- Clean and secure corroded or loose control-valve connector terminals.
- Repair wiring with excessive resistance or intermittent contact.
- Replace the control valve if its coil is outside specification or it fails an operation test.
- Repair the module circuit only after confirming the valve and wiring are sound.
Can I keep driving?
Limit driving if shifts are slipping, harsh, delayed, or the transmission enters limp mode, because incorrect pump pressure can damage internal parts. Stop if the transmission loses drive or cannot shift safely, and arrange prompt diagnosis.
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.