1996 GMC Sonoma Owner's Manual - Page 107

If the Light Is On Steady You may be able t o correct the emission system malfunction by considering the following: Did you just put fuel into your vehicle'? If so, reinstall the fuel cap, making sure to fully install the cap. The diagnostic system can determine if the fuel cap has been left off or improperly installed. This will allow fuel to evaporate into the atmosphere. A few driving trips should turn the light off. Did you just drive through a deep puddle 0 . f water'! If so. your electrical system may be wet. The condition w i l l usually be corrected when the electrical system dries out. A few driving trips should turn the light off. Have you recently changed brands of fuel? I f so, be sure to fuel your vehicle with quality fuel (see "Fuel" in the Index). Poor fuel quality will cause your engine not to run a s efficiently a s designed. You may notice this as stalling after start-up, stalling when you put the vehicle into gear. misfiring, hesitation on acceleration or stumblingon acceleration. (These conditions may go away once the engine is warmed up.) This will be detected by the system and cause the light t o turn on. I f you experience this condition, change the fuel brand you L I SIt will require a t least one full tank of the ~. proper fuel to turn the light off. If none of the above steps have made the light turn off, have your dealer orqualified service center check the vehicle. Your dealer has the proper test equipment and diagnostic tools to fix any mechanical or electrical problems that may have developed. Are you low on fuel? As your engine starts to run out of fuel. your engine may not run a s efficiently a s designed since small amounts of air are s ~ ~ c k e d the fuel line causing a misfire. The into system can detect this. Adding fuel should correct this condition. Make sure t o install the fuel cap properly. It w i l l take a few driving trips to turn the light off. 2-59