Evaporative Emission Control System prevents leaking of fuel vapors into the atmosphere by absorbing and storing them in the charcoal container. Absorbing action are provided by charcoal pellets. An OBDII Enhanced EVAP systems can purges vapors back to the engine to be injected to cylinders by standard methods.
In a simple explanation, there is a component called PCM and it responsible for testing EVAP system. He doing various tests into the system, operating in different time sets. The key how PCM knows that leaks occurring – is the pressure checking. An object to perform level of pressure testing is a fuel tank, and subject is the fuel tank pressure sensor, operated by PCM. The last frequently asking the sensor and if the low pressure level signal returned – P0456 error occures. It should be noted that this error code may not appear immediately, but only after the Powertrain Control Module (PCM) twice detects an error.
What are the Symptoms of Error P0456?
- When this error appears on the dashboard of the vehicle, the Check Engine indicator will light up and error P0456 will be saved in Engine Conrol Module (ECM) memory.
- Increased fuel consumption may occur (sometimes).
- Emissions, on the contrary, may rise up in such case (sometimes).
- Fuel smell is a case and also very dangerous thing - you should not miss it.
- The most common cause of error P0456 is a slight leak due to wear or damage to system components or hose connections.
- Other causes are loosening or damage to the fuel cap and damage to the purge and ventilation valves.
When diagnosing this error code, the car mechanic always performing the following:
- Reads all data and error codes stored onboard using the OBD2 scanner. If during checking the other codes are present, that are similar with level of fuel pressure or may have sense to fuel system, the diagnostics will extends to those codes first. Repairing them can help with the main code. If found the codes paired with P0441, P0440, and/or P0446, it is likely a short set of possible malfunctions: solenoid error, charcoal canister not tight, or even larger EVAP leak.
- He will check purge and ventilation valves including hose connections for damage.
- Check the ventilation valve for clogging with any kind of debris, which may result in the valve malfunctions.
- Smoke tightness test. It have sense to determine if a leak is present in the vapor recovery system and to try to correct the cause of the leak. Check if the fuel cap is well tightened and not damaged.
- Purge valve checking. Determines if it can hold a vacuum.
- Confidence that the cause of the error is a malfunction of the purge valve, while the problem is damaged or broken electrical wires
- Failure to perform a leak check and erroneous replacement of serviceable parts
- Do not contact the technical service bulletin from the automaker, which may indicate ways to resolve the error
- When error P0456 appears on the dashboard of the car, the Check Engine indicator will light up and the car will most likely not be able to pass the exhaust gas toxicity test.
- This error code indicates a very small leak in the fuel vapor recovery system, which in some vehicles will be difficult to detect. Error P0456 will appear until a leak has been detected and fixed.
- If the Check Engine indicator goes out, but the leak is not detected and eliminated, the car will still not be able to pass the exhaust gas toxicity test.
- Replacing the fuel tank cap
- Replacing a clogged or damaged ventilation valve
- Replacing a damaged purge valve
It should be noted, that error P0456 does not appear in all vehicles. If this error still appears in your vehicle and the Check Engine indicator lights up, the most common reason for its occurrence is damage to the fuel tank cap, purge valve, or ventilation valve, resulting in a very small leak.
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