What it means
Coolant bypass valve B is detected as stuck in the open position. The module sets this code when valve feedback or system behavior indicates that it remains open when it should move.
How it works
Coolant bypass valve B controls coolant routing in part of the thermal-management system. The module monitors valve position or system behavior and sets P0E7F when valve B remains open when it should move away from the open position; a jammed valve, failed actuator, debris, or an electrical fault can cause this.
Common causes
Most likely first.
- Valve jammed or internally damaged
- Debris or restriction in the valve
- Failed valve actuator
- Wiring or connector fault
Symptoms
- Hybrid or EV warning light
- Reduced power
- Battery or motor temperature warning
- Cabin heating or cooling may be reduced
How to diagnose it
- Record freeze-frame data and check live valve B command, position feedback if available, and coolant temperatures to see when the valve should have moved.
- Inspect valve B’s connector and harness for loose, corroded, or damaged connections that could interfere with movement or feedback.
- Check coolant level and inspect the accessible valve B coolant path for debris, leakage, or a restriction.
- Use a scan-tool actuator command if supported and compare valve B’s response with the manufacturer’s procedure.
- If the electrical command is present but the valve stays open, test actuator operation and mechanical movement according to the manufacturer’s instructions.
Common fixes
- Repair valve B wiring or connector faults that interfere with its command or feedback.
- Correct coolant loss and repair any leak found.
- Remove a confirmed obstruction from valve B’s path using the manufacturer’s procedure.
- Replace valve B if it is jammed open or its actuator has failed.
Can I keep driving?
Limit driving if reduced power or a battery or motor temperature warning appears, because a valve stuck open can disrupt thermal regulation. Stop safely if a temperature warning comes on.
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.