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Intake Air Temperature Sensor: Notes

NOTE: All voltage and continuity tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedures. For help with diagnostic testing. See WIRING DIAGRAMS .

Location of Intake Air Temperature (IAT) sensor and harness connection. See COMPONENT LOCATIONS .

  1. Allow engine to cool to room temperature approximately 68°F (20°C).
  2. Connect (VAG 1598) test box to ECM wiring harness using (VAG 1598/5) adaptor cable. See CONNECTING VAG 1598 TEST BOX . ECM is not connected.
  3. Using DVOM switched to resistance range. Connect DVOM between terminals No. 30 and 44 using adapter cables from (VW 1594) connector test kit. Resistance must be 450-650 ohms.
  4. If resistance is not correct, push back rubber boot on IAT sensor. Connect DVOM between sensor terminals and measure resistance again. If resistance is not correct, replace IAT sensor. See INTAKE AIR TEMPERATURE SENSOR REPLACEMENT .
  5. If resistance reading was correct, check wiring between sensor and ECM. Connect DVOM to terminal No. 30 of the test box and one after the other to the two sensor terminals. Readings must be respectively: Zero ohms (continuity) and 450-650 ohms.
  6. Repeat measurement using socket 44 of the test box. If NO, on either test: Repair open circuit or short circuit according to wiring diagram. See WIRING DIAGRAMS .
  7. Select "READ MEASURING VALUE BLOCK" function 08 using Scan Tool (VAG 1551) input display group number 03. See READING/MEASURING VALUE BLOCK (FUNCTION 08) under OUTPUT DIAGNOSTIC TEST MODES (DTM) in SELF-DIAGNOSTICS article. Check display in channel 4. INTAKE AIR TEMPERATURE displayed in degrees Celsius (°C).
  8. On an engine at room temperature, the intake air temperature immediately after start is somewhere in the range of ambient temperature. If an intake air temperature is indicated which, in comparison to the ambient temperature, seems incorrect, check wiring for short circuits.
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