What it means
The control module detects an open circuit or another electrical fault that prevents it from controlling coolant bypass valve D. The code sets when the valve control circuit does not respond as expected to a command.
At a glance
- Usually lights the check-engine light
How it works
Coolant bypass valve D is an electrically controlled valve that routes coolant through a particular part of the engine cooling system. The control module monitors valve D's control circuit and response to commands; this code sets when an open circuit or related electrical fault prevents the module from controlling the valve as expected.
Common causes
Most likely first.
- Open coil in bypass valve solenoid
- Broken control wire
Symptoms
- Check-engine light may be on
- Engine may take longer to warm up
- Coolant temperature may fluctuate
How to diagnose it
- Review freeze-frame data and scan-tool commands or feedback for bypass valve D to determine when the circuit fault occurred and whether it is currently present.
- With the engine cool, locate valve D using vehicle service information and inspect its connector and harness for breaks, chafing, corrosion, moisture, or loose pins.
- Test valve D's solenoid coil and compare the result with the manufacturer's specification to check for an open coil.
- With the circuit isolated as directed by the manufacturer, check continuity of the valve D control wire and inspect relevant connector contacts.
- If the wiring and coil pass, check the module-side control and circuit response using the manufacturer's procedure.
Common fixes
- Reconnect or repair a loose, corroded, or damaged valve D connector.
- Repair a broken valve D control wire.
- Replace the valve D solenoid if its coil is open by the manufacturer's test.
- Repair a confirmed module-side connection or control fault.
Can I keep driving?
If the temperature remains normal and stable, limit driving to a short trip for repair and monitor the gauge. Stop if the engine overheats or temperature fluctuates sharply, since valve D may not be routing coolant as needed.
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.