Description
When the control box is powered on it checks for the presence of a solenoid valve at regular intervals. Fault 4 occurs when no valve is detected. Upon clearing the fault, it will immediately trigger again until the issue causing the fault is resolved.
Causes
1. Loose or damaged solenoid cable
See Checking the cable.
2. Damaged solenoid
See Replacing a solenoid.
3. Damaged control box
On rare occasions the control box may experience a short circuit on the solenoid line. This can be caused by incorrect installation or crossing the solenoid wires. This causes irreparable damage to the control box and it will need to be replaced.