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DTC P0432/16816: MAIN CATALYST EFFICIENCY BELOW THRESHOLD (BANK 2) Audi A4 B5 facelift

Testing & Diagnostics ~356 words
  1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located before driver side 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If connector was repaired, erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.
  2. Ensure engine coolant temperature is at least 176°F (80°C). Turn ignition off. Disconnect HO2S connector. Start engine. Using a DVOM, check voltage between HO2S connector (harness side) terminals No. 3 and 4. Voltage should be .4-.5 volts. Turn ignition off. If voltage is within specification, replace HO2S. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article. If voltage is not within specification, go to next step.
  3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/22 test box to PCM wiring harness. Using DVOM, check resistance between HO2S connector (harness side) terminals and specified test box sockets: HO2S connector terminal No. 3 and test box socket 39. HO2S connector terminal No. 4 and test box socket 40. Resistance should be 1.5 ohms or less. If resistance is within specification, go to next step. If resistance is not within specification, repair wiring harness open as necessary. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.
  4. Using DVOM, check resistance between HO2S connector (harness side) terminal and specified test box socket. HO2S connector terminal No. 4 and test box socket 39. Resistance should be infinity. If resistance is infinity, go to next step. If resistance is not infinity, repair wiring harness short as necessary. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.
  5. Using DVOM, check resistance between HO2S connector (harness side) terminals and specified test box sockets: HO2S connector terminal No. 3 and test box socket 14. HO2S connector terminal No. 4 and test box socket 14. Resistance should be infinity. If resistance is infinity, replace faulty PCM. See PCM REPLACEMENT in SELF-DIAGNOSTICS - INTRODUCTION article. If resistance is not infinity, repair wiring harness short to wiring harness shielding as necessary. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS INTRODUCTION article.

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