Fuel Trim Cell Diagnostic Weights
WARNING: This page is about a different car, the 2002 Isuzu Trooper, 2002 Isuzu Rodeo Sport, 2002 Isuzu Rodeo, 2002 Isuzu Axiom, and 2002 Honda Passport. However, it is still accessible from the selected car via links, so may be relevant.
No fuel trim DTC will set regardless of fuel trim counts in cell "0" unless the fuel trim counts in weighted cells are also outside specifications. This means that vehicle could have a fuel trim problem causing a problem under certain conditions (i.e., engine idle high due to a small vacuum leak or rough due to a large vacuum leak) while it operates fine at other times. No fuel trim DTC would set (although an engine idle speed DTC or Heated Oxygen Sensor DTC may set). Use scan tool to observe fuel trim counts while problem is occurring.