After-Burn In Exhaust System
- Check Intake Manifold Pressure (IMP) sensor (Legacy and Outback).
- Check Intake Air Temperature (IAT) sensor (Legacy and Outback).
- Check intake air temperature and pressure sensor.
- Check Mass Air Flow (MAF) sensor (Impreza DOHC).
- Check Engine Coolant Temperature (ECT) sensor, if symptom occurs only in cold temperatures.
- Check fuel injection components; fuel injectors, fuel pressure regulator and fuel filter.
- Check fuel pump and fuel pump relay.