2008 Dodge Magnum Owner Manual SRT8 - Page 384
2008 Dodge Magnum Manual
Page 384 highlights
382 MAINTAINING YOUR VEHICLE Loose Fuel Filler Cap If the vehicle diagnostic system determines that the fuel filler cap is loose, improperly installed, or damaged, a "Check Gascap" message will display in the Electronic Vehicle Information Center (EVIC) (if equipped). If this occurs, tighten the fuel filler cap properly and press the TRIP ODOMETER button to turn off the message. If the problem continues, the message will appear the next time the vehicle is started. A loose, improperly installed, or damaged fuel filler cap may also turn on the MIL. EMISSIONS INSPECTION AND MAINTENANCE PROGRAMS In some localities, it may be a legal requirement to pass an inspection of your vehicle's emissions control system. Failure to pass could prevent vehicle registration. For states that require an I/M (Inspection and Maintenance), this check verifies the MIL is functioning and is not on when the engine is running, and that the OBD II system is ready for testing. Normally, the OBD system will be ready. The OBD II system may not be ready if your vehicle was recently serviced or recently had a dead battery or had a battery replacement. If the OBD II system should be determined not ready for the I/M test, your vehicle may fail the test. Your vehicle has a simple ignition key-actuated test, which you can use prior to going to the test station. To check if your vehicle's OBD II system is ready, you must do the following: 1. Insert your ignition key into the ignition switch. 2. Turn the ignition to the ON position, but do not crank or start the engine.