Because it is a flow code then it would help to know what the ECU uses to ref it. (I don’t know) MAP/MAF, throttle position and engine speed possibly. Check all the pipework as well as both the valve and solenoid. If that’s all ok then look at the other signals that may be involved.

From ross tech wiki -


16825/P0441/001089 - EVAP Emission Control Sys: Incorrect Flow

Possible Symptoms
Malfunction Indicator Light (MIL) active

Possible Causes
Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80) faulty/jammed
Evaporative Emission (EVAP) Canister Purge Solenoid Valve (N115) faulty/jammed
Evaporative Emission (EVAP) Canister Sealing faulty
Pipes between Tank Breathing and Throttle Body leaky/blocked

Possible Solutions
Check Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80)
Perform Output Test
Check Evaporative Emission (EVAP) Canister Purge Solenoid Valve (N115)
Check Evaporative Emission (EVAP) Canister
Perform Basic Setting
Check Pipes between Tank Breathing and Throttle Body