Oxygen Sensor Control
- Ensure base settings for ignition and idle are okay. Ensure exhaust system is not leaking between catalytic converter and cylinder head. Ensure voltage supply for oxygen sensor heater is okay.
- Connect Scan Tester (VAG 1551) to DLC, located below A/C-heater control panel. See the TESTS W/CODES
article. With scan tester in READ MEASURING VALUE BLOCK function, ensure coolant temperature is greater than 176°F (80°C), as displayed in field No. 2 of scan tester.
- Allow engine to run for 2 minutes at idle, then read oxygen sensor factor (signal) in field No. 3 of scan tester. Display value must fluctuate. If value in display field No. 3 does not fluctuate, briefly accelerate engine and repeat test.
- If oxygen sensor value does not change even during acceleration, disconnect engine coolant temperature sensor. Erase Diagnostic Trouble Code (DTC) memory. Disconnect oxygen sensor wiring harness connector.
- Ground oxygen sensor wiring harness connector terminal No. 4. See Fig 1
. Value in display field No. 3 must increase. If value increases, replace oxygen sensor. If value does not change, repair circuit or replace ECM as necessary. After repairs, erase DTC memory (if applicable) and select END OUTPUT function.
Courtesy of VOLKSWAGEN UNITED STATES, INC.