Circuit Description
WARNING: This page is about a different car, the 2006 Saturn Ion 3 and 2006 Saturn Ion 2. However, it is still accessible from the selected car via links, so may be relevant.
The engine control module (ECM) uses the following information to calculate an expected airflow rate:
- The throttle position (TP)
- The barometric pressure (BARO)
- The manifold absolute pressure (MAP)
- The intake air temperature (IAT)
- The mass air flow (MAF)
- The engine RPM
If the ECM detects the airflow rate is more than expected, DTC P0121 sets.