GM Service Manual Online
For 1990-2009 cars only

FALSE SETTING-TROUBLE CODE 31 WIDE OPEN THROTTLE DOWNSHIFT

THE 1.8L TURBO (LA5) ENGINE IN THE "J" SERIES MAY ENCOUNTER A MOMENTARY FUEL SHUT-OFF (SAG) CONDITION. IF THE CAR IS DRIVEN AT A STEADY LIGHT BOOST CONDITION (APPROXIMATELY 2-3 PSI BOOST) AND THE DRIVER GOES TO WIDE OPEN THROTTLE WITH A DOWNSHIFT FOR MORE THAN TWO SECONDS. THE ENGINE WILL SHUT-OFF THE FUEL FOR A SHORT PERIOD OF TIME (APPROXIMATELY ONE SECOND), BECAUSE OF AN OVERBOOST CONDITION, THEN COME ON AGAIN, AND EVERYTHING WILL RETURN TO NORMAL. DURING THIS TIME, THE "CHECK ENGINE" LIGHT WILL COME ON, AND CODE 31 WILL BE STORED. DIAGNOSIS FOR CODE 31 WILL FIND NO PROBLEMS. IT SHOULD BE EMPHASIZED THAT THIS CONDITION IS VERY UNLIKELY TO OCCUR IN NORMAL DRIVING. TO REPAIR THIS FALSE CODE CONDITION, REPLACE THE PROM WITH THESE PART NUMBERS: PART NUMBER 1226928 - CALIFORNIA PART NUMBER 1226929 - FEDERAL

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.