What it means
Voltage on the second coolant bypass valve control line is above the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The control module drives the solenoid for coolant bypass valve B to regulate a second coolant path. This code sets when voltage on valve B's control circuit rises above the expected range, which can happen with a short to battery voltage or an open solenoid coil.
Common causes
Most likely first.
- Control wire shorted to B+
- Open solenoid coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Engine temperature may fluctuate
- Heating or warm-up may be affected
How to diagnose it
- Capture freeze-frame data and check valve B command and circuit data to see when the high reading is detected.
- Inspect bypass valve B's solenoid connector and control harness for an open connection, corrosion, damaged insulation, or contact with a battery-voltage wire.
- With the fault active, gently move the harness near valve B while watching circuit data or code status for an intermittent change.
- Check the control wire for a short to battery voltage and test the solenoid coil for an open, using the wiring information and manufacturer's specification.
- If the wiring and coil check out, verify the module's control output and connector contacts under the manufacturer's test procedure.
Common fixes
- Reconnect the valve B solenoid connector and repair damaged or corroded terminals.
- Repair the control wire if it is shorted to battery voltage or open.
- Restore a poor circuit connection at the solenoid connector.
- Replace the bypass valve B solenoid if its coil is open.
Can I keep driving?
If engine temperature remains normal, keep driving gentle and monitor the gauge because bypass valve B may not regulate its cooling path. Stop if temperature rises above normal or the engine overheats.
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.