2009 Hummer H3T Alpha Owner's Manual - Page 149

Instrument Panel the vehicle's fuel economy might not be as good, and the engine might not run as smoothly. This could lead to costly repairs that might not be covered by the vehicle warranty. Notice: Modifications made to the engine, transmission, exhaust, intake, or fuel system of the vehicle or the replacement of the original tires with other than those of the same Tire Performance Criteria (TPC) can affect the vehicle's emission controls and can cause this light to come on. Modifications to these systems could lead to costly repairs not covered by the vehicle warranty. This could also result in a failure to pass a required Emission Inspection/Maintenance test. See Accessories and Modifications on page 5-3. This light comes on during a malfunction in one of two ways: Light Flashing: A misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Diagnosis and service might be required. The following can prevent more serious damage to the vehicle: 3-31 Light On Steady: An emission control system malfunction has been detected on the vehicle. Diagnosis and service might be required. An emission system malfunction might be corrected by: • Make sure the fuel cap is fully installed. See Filling the Tank on page 5-7. The diagnostic system can determine if the fuel cap has been left off or improperly installed. A loose or missing fuel cap allows fuel to evaporate into the atmosphere. A few driving trips with the cap properly installed should turn the light off. Reduce vehicle speed. Avoid hard accelerations. Avoid steep uphill grades. If towing a trailer, reduce the amount of cargo being hauled as soon as it is possible. • If the vehicle has been driven through a deep puddle of water, the vehicle's electrical system might be wet. The condition is usually corrected when the electrical system dries out. A few driving trips should turn the light off. If the light continues to flash, when it is safe to do so, stop the vehicle. Find a safe place to park the vehicle. Turn the key off, wait at least 10 seconds, and restart the engine. If the light is still flashing, follow the previous steps and see your dealer/retailer for service as soon as possible.