The warning “Evaporative Emission System Leak Detected” is displayed with the fault code P0457. The powertrain control module will set fault code P0457 if it detects a significant EVAP leak. The leak is often caused by a missing or loose fuel cap. Related fault codes for minor and moderate EVAP system leaks are the P0455 and P0456.
The Evaporative Emission System is designed to stop fuel vapours escaping into atmosphere and causing pollution. The PCM will record codes P0455, P0456 or P0457 if a leak is detected in this system. The codes are similar but differ in severity. The P0457 code represents the worst emission leak while the P0455 code represents the smallest. The P0456 code is in the middle.
The following components are included in a typical EVAP system:
- Fuel tank
- Fuel tank cap
- A sensor that measures pressure in the tank of fuel
- Canister for storing fuel vapours
- Vent valve
- A valve that shuts off during system testing
- Hoses and pipes for connecting the system
All these components are centered around the canister which stores fuel vapours even when the engine is not running.
The PCM will open the vent valve when the engine is running, and all conditions are met. The PCM opens the vent valve to allow fuel vapours into the engine, where they are burned in the normal combustion process.
Vehicles built after 1996 come equipped with EVAP systems. The PCM checks the EVAP for both leaks in the system and burning fuel vapours. A fault code is set if a leak in the system is detected.
Unstable fuel tank caps can cause EVAP leaks. Fuel vapours can escape if the cap is not snugly seated in the socket.
Many vehicles are able to check if refuelling took place by monitoring parameters like the ignition key or fuel level. The PCM will set the P0457 code if it detects a leak in the EVAP system shortly after refuelling. This code can be set by any major leak, regardless of the cause.
Table of Contents
What are the causes of fault code P0457?
Fuel vapour can be released from the system by several means:
- A cracked, missing or loose fuel tank lid
- Hoses that are cracked or rotten
- A broken canister drum
- Fuel filler neck damaged
What are the P0457 Fault Code Symptoms?
- Engine fault light illuminated
- Fuel odour
- Fuel consumption increases slightly
How to Fix Fault Code P0457?
- The tank cap should be inspected visually. If it has cracks, wear or dirt on its teeth, or any other problem, the cap should be cleaned or changed.
- The fault code must be cleared after the procedure and then checked to see if the error returns.
- Check the EVAP system thoroughly if the problem is not due to the tank cap.
- Replace hoses that are worn and corroded.
- If there are any cracks or leaks, the intake manifold connections should be replaced.
- If the canister tank has a crack, it needs to be replaced.
How Serious is Error Code P0457?
The fault code P0457 does not generally affect the vehicle’s drivability, but is the most serious one related to EVAP leaks. Fuel consumption and emission values may rise. It is possible that if you do nothing, the leaks will get bigger and more expensive.
