E4 error appears and the unit stops spraying solution; suction and brush may still operate.

Safety first: Unplug the Philips carpet cleaner and remove the water tanks.

• Check water and detergent levels: Ensure the clean water tank is filled to the correct level and properly seated. Verify that any detergent cartridge or dosing compartment is correctly installed.
• Inspect tank valves: On Philips tanks with spring-loaded valves, press the valve with your finger over a sink to confirm water flows. If stuck, rinse under warm water and gently free the valve.
• Clean spray nozzles: Locate the front spray bar or nozzles. Remove any clip-on covers and soak the nozzles in warm water. Use a soft brush or toothpick to clear mineral deposits or debris.
• Check solution hose: Follow the clear solution hose from the tank to the pump and from the pump to the spray bar. Look for kinks, pinches, or disconnections. Reseat any loose push-fit connectors.
• Prime the pump: Refill the tank, reinstall it, then with the unit powered on, hold the trigger for 30–60 seconds over a sink or bucket to purge air. If no spray and E4 returns, the pump or flow sensor may be defective.
• Component replacement: If the pump is noisy but no water moves, it may be blocked or failing. Replace the solution pump assembly. If the pump runs and sprays but the unit still shows E4, the flow sensor on the solution line may be faulty and should be replaced or the main PCB updated.