Sensor Checks
- Check the Engine Coolant Temperature (ECT) sensor using a scan tool to compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 9°F (5°C) more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or in the sensor. See TEMPERATURE VS. RESISTANCE table.
- Inspect the Mass Air Flow (MAF) sensor operation. Run engine to normal operating temperature. Turn OFF all accessories and observe the MAF sensor at idle with a scan tool. If the MAF sensor reading is more than 3.5 g/s, see DTC P0101: MAF SENSOR PERFORMANCE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 1.8L VIBE article.