To provide a controller for a compression ignition internal combustion engine capable of preventing drivability and fuel economy performance from being adversely affected by determining operation of a gas temperature adjusting means for adjusting gas temperature in a combustion chamber and switching from spark ignition operation to compression ignition operation.

This controller determines whether operation of the gas temperature adjusting means for adjusting gas temperature in the combustion chamber such as a variable valve mechanism is normal or not (S118, S120, S122, S124) and inhibits switching from spark ignition operation to compression ignition operation when it is determined that the operation of the gas temperature adjusting means is not normal (S110).

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