Error Code P0457 is defined as Evaporative Emission Control System Leak Detected, which means a leak in the Evaporative Emission Control has been detected, which is most commonly caused by missing, cracked, or loose gas cap.

This error code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.


Error Code P0457 refers to a vacuum leak in the evaporative emission system. The system works by keeping fuel vapor leaks from escaping to the atmosphere. This leak is detected by the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes).

The Evaporative Emission Control system is designed to keep fuel vapor from leaking out into the atmosphere, causing pollution. If there is a leak in the system, the codes P0455, P0456, and P0457 will be stored by the PCM. These codes are similar and only differ in the severity of the leak. P0455 is the less severe, while P0457 refers to the most severe emission leak.

Common Symptoms

Generally, EVAP-related codes don’t usually affect the performance and drivability of the vehicle, and this includes this Error Code. But since it’s the most severe emission leak, it may cause problems in the fuel efficiency of the vehicle if the tank is large enough.

In most cases, however, this error code doesn’t show a lot of symptoms other than the illuminated Check Engine light. Also in some cases, there may be occasional fuel smell caused by the leak.

Possible Causes

Since this code is only stored when there is truly a large leak, then we can rule out a number of smaller issues that may cause P0455 and P0456. In most cases, the P0457 is caused by:

  • Cracked, loose, or missing gas cap
  • Cracked vacuum canister
  • Cracked or rotten hose

Since the system is protected from the elements, the P0457 usually doesn’t result in the weather damaging the system parts and other related instruments.

How to Check

Since this code doesn’t usually come with a lot of symptoms other than the activation of the Check Engine light, it is important for technicians to start their diagnosis using an OBD-II scanner to inspect and detect the code thoroughly. Once the P0457 is identified and verified, technicians will start their visual inspection of the vehicle, starting with the gas cap.

If the gas cap is cracked, worn out, missing, or has some foreign object in the thread keeping it from completely sealing, then it must be replaced. The code must be cleared, and the vehicle must be taken for a test drive to see if the code comes back.

If the code persists and the problem is not in the gas cap, then the mechanic will proceed on checking the rest of the Evaporative Emission Control system and check the wires and the sensor further.

The mechanic will also inspect the vacuum hoses; check the fitting of the intake manifold for cracks where the emission hose connects, and also check for cracks in the charcoal canister.

Lastly, the mechanic will place a vacuum pump on the emission hose (at the side of the engine) and pump it up to about 10 inches of vacuum. If there are no leaks, the vacuum will hold its position. If it drops, then that means there is a leak between the purge valve on the canister and the engine.

How to Fix

As with many Evaporative Emission Control System error codes, the P0457 is easy to repair; the most common repair is ensuring the gas cap is in place and tightly seals. If it can’t, then it must be replaced.

Other repairs include:

  • Replacement of one or more hoses in the Evaporative Emission Control system
  • Ensuring the fitting of Intake Manifold is sealed and free of cracks, if not, then they must be replaced
  • Replacement of cracked charcoal canister

Since this error code refers to the most severe vacuum leak condition, it must be properly addressed as soon as possible, as it can cause higher fuel emission with a decrease in fuel efficiency of the vehicle.

Depending on the severity of the problem, this leak could result in a larger leak later on, which obviously can be more expensive and can keep the vehicle from running until it’s been solved.