An ECU executes a program including a step (S102) of limiting the maximum
opening amount of a throttle valve to TH (1) when failure has occurred in
a pressure sensor ("YES" in step S100); a step (S202) of limiting the
maximum opening amount to TH (2) when open failure has occurred in at
least one of two vacuum pressure ASVs provided for banks of a V-type
engine, and an electromagnetic ASV ("YES" in step S200); a step (S302) of
limiting the maximum opening amount to TH (3) when open failure has
occurred in both of the vacuum pressure ASVs ("YES" in step S300); a step
(S402) of limiting the maximum opening amount to TH (4) when open failure
has occurred in one of the vacuum pressure ASVs ("YES" in step S400); and
a step (S502) of reducing the throttle valve opening amount TH to the
limited maximum opening amount.