Technical Description of OBD-II Trouble Code
A small leak in the Evaporative Emission Control System has been detected.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to many OBD-II equipped vehicles. While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle. This code can be found on various makes including Ford, GMC, Jeep, Dodage, Toyota, BMW, Chrysler, Subaru, etc.
The vehicle’s PCM (powertrain control module) tests the evaporative emissions (EVAP) system for both large and small leaks, among other conditions. In the case of this DTC, it indicates a fuel vapor leak in the EVAP control system. It means that a very small leak has been detected, even as small as a hole with a diameter of 0.04″. The EVAP emission control system is responsible for preventing the escape of fuel vapors from the vehicle’s fuel system.
Fuel vapors are directed through hoses to a charcoal canister for storage. When the engine is running, a purge control valve opens, allowing intake vacuum to draw the fuel vapors into the engine to be burned. This process helps reduce vehicle emissions.
Photo of a typical gas cap:
Symptoms
The only noticeable symptom is that the Malfunction Indicator Lamp (MIL), also known as the Check Engine Light, will be illuminated. You may not experience any drivability issues, although sometimes a fuel odor may be detected.
Causes
A code P0442 most likely indicates one or more of the following:
Possible Solutions
For a P0442 code, the most common DIY repair is to:
More advanced troubleshooting steps include:
Generally, there are specific procedures for diagnosing this DTC based on the vehicle and model.
Other EVAP DTCs: P0440 – P0441 -P0443 – P0444 – P0445 – P0446 – P0447 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456
