Insufficient Fueling

With this condition, the engine may actually run lean of stoichiometry (14.7:1 air to fuel ratio) if the PCM is not able to compensate enough to correct for the condition. This condition can be caused by a fuel delivery system concern that restricts or limits the amount of fuel being delivered to the engine. This condition normally is most apparent when the engine is under a heavy load and at high RPM, when a higher volume of fuel is required. If the freeze frame data indicates the fault occurred under a heavy load and at higher RPM, a check of the fuel delivery system (checking fuel pressure with engine under a load) might be the best starting point.

For example, low fuel pressure, fuel pump, fuel filter, fuel leaks, restricted fuel supply lines, and fuel injector concerns.