P0496 Fault Code

Long Description

Fault code P0496 is logged when an undesirable evaporative emission control system (EVAP) flow during a non-purge condition is detected. This occurs when the engine control unit (ECU) has detected flow in the EVAP system when it should be sealed.

This code can also be called “EVAP Flow During a Non-Purge Condition” depending on the manufacturer.

The purpose of the EVAP system is to prevent fuel vapors from being released into the atmosphere. This is done to comply with emissions requirements and has been a requirement since the 1970s.

The EVAP system itself does not strongly influence the day-to-day operations of a vehicle.

A purge condition is when the EVAP purge valve is triggered to open as a result of the desired pressure being reached in the fuel tank. This allows the flow of fuel vapors from the EVAP system into the engine at specific times.

It is mandatory for all vehicles to have an EVAP system to reduce emissions. This means any car can suffer this fault code but manufacturers like Cadillac, Chevrolet, and GMC are some of the most commonly affected.

Other Signs of This Problem

Faults in the EVAP system are notoriously difficult to detect from symptoms alone. Very few signs could indicate unwanted flow in the EVAP system, making it hard to determine without the error code.

The most obvious sign is that the Check Engine light may be on.

Another indicator could be the vehicle running slightly richer than normal as unexpected fuel vapors enter the combustion chamber.

Look out for any other codes relating to the EVAP system. These are fault codes like P0440, P0441, and P0456.

What Could Be The Problem?

All of the potential causes are likely to be found within the EVAP system and its components. There could also be electrical components that are failing.

The purge vent valve or solenoid could be stuck open or altogether faulty – leading to this P0496 fault code. This will allow flow through the EVAP system even if the ECU has not initiated it.

Similarly, faulty wiring to the purge vent can cause it to stay open.

Another potential cause is a faulty EVAP pressure sensor. This can send a signal to the ECU that there is sufficient pressure for the purge vent to open, without actually having enough pressure.

A leaking charcoal canister can also cause unwanted flow in the system.

Fixes

Most fixes for this error are relatively simple. These involve correcting issues with wiring and connections or replacing faulty parts.

One of the most common fixes is to replace a faulty purge vent valve or solenoid. It is also a good idea to check the wiring and connections between this valve and the ECU to determine if they are in working order.

Another component that should be checked is the fuel pressure sensor. It is important to replace a faulty sensor. Its wiring and connections should also be checked and repaired.

It is also good practice to check that the gas cap is properly fastened whenever EVAP-related codes are logged.

Seriousness

Fault code P0496 ranks low in terms of severity. There is no risk of damage to yourself or the vehicle.

It should be fixed to prevent losses in the fuel tank, ideally within a few weeks, especially as it can cause your vehicle to run rich and decrease fuel economy.