P0441 Evaporative fuel evaporation system – erroneous cleaning flow
OBD2 error P0441 possible causes
The reasons that may lead to the establishment of code P0441 may be the following:
- Missing fuel filler cap
- Wrong fuel filler cap
- Evaporative evaporator valve (evap) malfunction
- Breaked pipe for the evaporation of fuel vapour into the suction manifold
- Compact, damaged or corroded wires and/or connectors.
- Leakage of pressure lines
Code P0441 means that the control module has detected a leakage from EVAP (Evaporation Emission).
A loose fuel filler cap is the most common cause that triggers code P0441.
When will the code be detected?
- The pressure in the activated charcoal tank and the fuel tank does not drop when controlling the evaporator valve
- Activation of the engine failure indicator
- Possible perceptible fuel odour caused by the release of fuel vapour
The engine control module (ECM) tests the EVAP system under the following conditions: – Large and small leaks – Excessive vacuum – Cleaning flow in non- command conditions – Fault in fuel level and fuel pressure sensor – EVAP Purge and vent valve faults The ECM monitors the fuel tank pressure sensor to determine the vacuum/pressure level in the EVAP system. The ECM module instructs both the EVAP solenoid valve and the EVAP vent valve to be turned on when the appropriate conditions are met to apply engine vacuum to the EVAP system. ECM orders the EVAP solenoid valve to be turned off when the system reaches a specified vacuum level. This test checks if vacuum in the EVAP system can be achieved. Failure to achieve vacuum may be caused by a large leak or flow limitation.
What does code P0441 mean?
Fault code OB0 II P0441 is defined as ‘Evaporative Emission Control System Incorrect Flow’ and is set when PCM (power unit control unit) detects that a part of the EVAP (Evaporative Emission Control) system is not working properly. Typical EVAP systems consist of a fuel tank, fuel filler cap, pressure and flow sensors, activated carbon tank, vent valve with control solenoid valve, fuel and vacuum hoses, fuel hoses and electrical hoses/connectors.
The various sensors in the EVAP system convert changes in pressure or flow rate in the system into signal voltages, which PCM compares with predefined values. When the PCM receives a signal voltage that does not match the expected value for a particular operating condition, the code will be saved and a warning light may come on. It should be noted that while most applications will trigger the warning on the first failure, several applications require several error cycles before the warning light comes on.
The function of EVAP is to capture fuel vapors before they can escape into the atmosphere. The fuel vapors are collected and either passed through an activated carbon canister in which activated carbon stores the vapor before it is passed to the inlet channel through a network of hoses to be burned as part of the fuel-air mixture when operational conditions allow. The flow rate of the collected vapour is controlled by a vent valve that opens or closes gradually in response to signals sent to it from the PCM, which in turn receives pressure-based signals from the EVAP pressure sensors.
Note that the rate at which the fuel vapour is delivered to the engine for combustion is not constant. For example, when the engine is under heavy load, which requires additional fuel, PCM orders the EVAP system to deliver large amounts of fuel vapor. Conversely, when the engine is under constant load, the available fuel vapor will be released slowly and gradually, with oxygen sensors used to warn PCM when the air/fuel mixture reaches an excessively rich state, at which point PCM will reduce the rate of steam flow.