2009 Hyundai Sonata 61000 mi.Check engine light on com.puter scan code 0456.Sml leak evap canister,purge valve stuck open..One day later check engine light no longer on.Next step?

Most likely is a bad EVAP purge valve. But check below list.
This indicates that a part of the EVAP control system is no longer functioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

EVAP emission canister purge is controlled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set.
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Likely, no symptoms will be discernible to the driver, other than the illuminated Check Engine Light.
Causes

A code P0441 could mean one or more of the following has happened:

• Bad vacuum switch
• Broken or damaged EVAP line or canister
• Open in PCM purge command circuit
• Open or short in Voltage feed circuit to Purge Solenoid
• Faulty purge solenoid
• Restriction in EVAP solenoid, line or canister
• Corrosion or resistance in purge connector
• Bad PCM

Possible Solutions

With a P0441 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

• Replace Leak Detection Pump / LDP
• Repair damaged EVAP lines or canister
• Repair open or short in voltage feed circuit to Purge Solenoid
• Repair open in PCM purge command circuit
• Replace purge Solenoid
• Replace vacuum switch
• Repair restriction in Evap line or canister or solenoid
• Repair resistance in purge connector
• Replace PCM

P0441 Evaporative Emission Control System Incorrect Purge FlowOBD-II Trouble Code Technical Description

Evaporative Emission Control System Incorrect Purge Flow
What does that mean?

This indicates that a part of the EVAP control system is no longer functioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

EVAP emission canister purge is controlled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set.
Symptoms

Likely, no symptoms will be discernible to the driver, other than the illuminated Check Engine Light.
Causes

A code P0441 could mean one or more of the following has happened:

• Bad vacuum switch
• Broken or damaged EVAP line or canister
• Open in PCM purge command circuit
• Open or short in Voltage feed circuit to Purge Solenoid
• Faulty purge solenoid
• Restriction in EVAP solenoid, line or canister
• Corrosion or resistance in purge connector
• Bad PCM

Possible Solutions

With a P0441 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

• Common Chrysler fix - Replace Leak Detection Pump / LDP
• Repair damaged EVAP lines or canister
• Repair open or short in voltage feed circuit to Purge Solenoid
• Repair open in PCM purge command circuit
• Replace purge Solenoid
• Replace vacuum switch
• Repair restriction in Evap line or canister or solenoid
• Repair resistance in purge connector
• Replace PCM

Other EVAP DTCs: P0440 - P0441 - P0442 - P0443 - P0446 - P0453 - P0455 - P0456

code p 0441 refers to evaporative emission (EVAP) system --incorrect flow detected ==== causes --- hose connection/s--- intake leak---EVAP canister purge valve replace the purge valve

What are my problems ????? Without testing we'd only be guessing . A lot of electronic's ,software , electrical ,sensors etc.... Hooking up a factory scan tool an viewing data input's an outputs from the different control modules on the vehicle is what should be done by a qualified technician . With any DTC - diagnostic trouble code their are diagnostic test's that need to be done an done correctly so parts are not replaced needlessly . Don't know what kind of scanner was used to pull the code P1440 but this is not a code for your vehicle . I would try a different repair shop .

EVAP System Vent Circuit Malfunction

This diagnosis detects leaks in the Evaporative Emission (EVAP) purge line using of vapor pressure in the fuel tank. The EVAP canister vent control valve is closed to shut the EVAP purge line. The vacuum cut valve bypass valve will then be opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP control system pressure sensor can now monitor the pressure inside the fuel tank. If pressure increases, the Engine Control Module (ECM) will check for leaks in the line between the vacuum cut valve and EVAP canister purge volume control solenoid valve.

Possible causes
- Incorrect fuel tank vacuum relief valve
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve
- Foreign matter caught in EVAP canister vent control valve
- EVAP canister or fuel tank leaks
- EVAP purge line (pipe and rubber tube) leaks
- EVAP purge line rubber tube bent
- Blocked or bent rubber tube to EVAP control system pressure sensor
- Loose or disconnected rubber tube
- EVAP canister vent control valve and the circuit
- O-ring of EVAP canister vent control valve is missing or damaged
- EVAP canister is saturated with water
- EVAP control system pressure sensor
- Absolute pressure sensor

Possible solution
- Loose fuel filler cap
- Leaking fuel filler cap


Hope helps (remember to rate this answer).

Which code specifically? Do not assume you need a new solenoid. Our recommendation will depend on the specific code and some troubleshooting results. I usually recommend checking over all the EVAP vacuum lines and the gas cap too whenever there is a purge valve code. Check the vacuum lines at the cannister in the left rear bumper. I will paste info on the purge solenoid below.

P0440 Evaporative emission (EVAP) system - malfunction

Possible causes: Hose connection(s), intake leak, EVAP canister purge valve

P0441 Evaporative emission (EVAP) system - incorrect flow detected

Possible causes: Hose connection(s), intake leak, EVAP canister purge valve

P0442 Evaporative emission (EVAP) system - small leak detected

Possible causes: Hose connection(s), intake leak, EVAP canister, EVAP canister purge valve

P0443 Evaporative emission (EVAP) canister purge valve - circuit malfunction

Possible causes: Wiring, EVAP canister purge valve, ECM

P0444 Evaporative emission (EVAP) canister purge valve -open circuit

Possible causes: Wiring open circuit, EVAP canister purge valve, ECM

P0445 Evaporative emission (EVAP) canister purge valve -short circuit

Possible causes: Wiring short circuit, EVAP canister purge valve, ECM

P0450 Evaporative emission (EVAP) pressure sensor - circuit malfunction

Possible causes: Wiring, EVAP pressure sensor, ECM

P0455 Evaporative emission (EVAP) system - large leak detected

Possible causes: Hose connection(s), intake leak, EVAP canister, EVAP canister purge valve

P0456 Evaporative emission system - very small leak detected

Possible causes: Mechanical fault, hose connection(s), EVAP pressure "sensor

P0457 Evaporative emission system - leak detected (fuel cap loose/off)

Possible causes: Mechanical fault, hose connection(s), EVAP pressure sensor

P0458 Evaporative emission system, purge control valve -circuit low

Possible causes: Wiring short to earth, EVAP valve

P0459 Evaporative emission system, purge control valve -circuit high
Possible causes: Wiring short to positive, EVAP valve

Evaporative Emission Purge Solenoid

Description & Operation
The duty cycle EVAP canister purge solenoid (DCP) regulates the rate of vapor flow from the EVAP canister to the intake manifold. The Powertrain Control Module (PCM) operates the solenoid.
During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.
The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM cycles (energizes and de-energizes) the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time that the solenoid is energized. The PCM adjusts solenoid pulse width based on engine operating condition.
Removal & Installation
The duty cycle evaporative (EVAP) canister purge solenoid is located in the engine compartment near the brake master cylinder.

1. Disconnect electrical connector at solenoid.
2. Disconnect vacuum lines at solenoid.
3. Lift solenoid slot from mounting bracket for Removal & Installation.

To Install:

1. Position solenoid slot to mounting bracket.
2. Connect vacuum lines to solenoid. Be sure vacuum lines are firmly connected and not leaking or damaged. If leaking, a Diagnostic Trouble Code (DTC) may be set with certain emission packages.
3. Connect electrical connector to solenoid.
   

Purge solenoid location:


EVAP cannister location:

Purge Control Valve Problem

The "Purge Control Solenoid Valve" is the "Purge Control Valve".

Rough idle is a typical symptom of something amiss with the purge control portion of the evaporative emissions system. It could be the valve itself is not operating correctly, the evap canister (vapor canister) may be leaking, or full of raw gas instead of vapor, or maybe even the purge control valve is getting a faulty signal from the ECU.

The soleniod is checked by applying a voltage to it and checking to see if it closes, or opens (I'm not sure if its un-energized state is normally open, or normally closed). If the valve is bad it is a no-brainer to replace.

The vapor canister can be removed and checked to see if it is full of raw gas (not supposed to be), but checking it for leaks is a bit involved, and probably requires equipmet not normally owned by a home mechanic. Vapor canister failure on cars with a lot of miles is common. Replacement is the fix.

Of course if the ECU is not sending a purge signal to the valve correctly, figuring out why may proove difficult, and possibilities could even include a faulty ECU. I expect this is unlikely though.

It's a $20 part. I first would change pcv valve because it can give same error if it's plugged up. You can always remove it and shake it. It should rattle around real easy. If not, it should be repalced

maybe a fuse is blown? did you have the mechanic check the fuses? or even check all your relays and wiring?

CODE PO455 EVAPORATIVE EMISSION SYSTEM LARGE LEAK DETECTED.POSSIBLE CAUSES CANISTER VENT SOLENOID MAY BE STUCK IN OPEN POSITION / EVAP CANISTER TUBE EVAP CANISTER PURGE OUTLET TUBE OR EVAP RETURN TUBE DISCONNECTED OR CRACKED OR CANISTER IS DAMAGED / EVAP CANISTER PURGE VALVE STUCK CLOSED OR CANISTER DAMAGED / FUEL FILLER CAP MISSING LOOSE NOT TIGHT OR THE WRONG PART / FUEL VAPOR HOSES TUBES BLOCKED OR RESTRICED OR FUEL VAPOR CONTROL VALVE TUBE OR FUEL VAPOR VENT VALVE ASSEMBLY BLOCKED /FUEL TANK PRESSURE SENSOR HAS FAILED MECHANICAL FAULT /FUEL TANK CONTROL VALVE IS CONTAMINATED DAMAGED OR HAS FAILED.

Gas cap tight?

• A small leak in any of the EVAP hoses or fuel tank hoses
• A small leak in the purge valve or vent valve
• The EVAP Canister may be leaking.