- Air leak between the MAF sensor and throttle body.
- TP sensor not seated properly.
- Damaged TP sensor.
- Damaged MAF sensor.

On some ION models the problem is an intake leak

- Engine Light ON(or Service Engine Soon Warning Light)
- Lack/Loss of power
- Engine rough idle

The PCM monitors a vehicle operation rationality check by comparing Throttle Position (TP) to Mass Air Flow (MAF) readings. If, during a self-test, the comparison of the TP sensor and MAF sensor readings are not consistent with the calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory.