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HOMESERVICE MANUALSAUDI1996A4 BASE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - 2.8LCIRCUIT TESTSDTC P0154/16538 - HO2S CIRCUIT NO ACTIVITY DETECTED (BANK 2, SENSOR 1)
1996 Audi A4 Base, Standard

DTC P0154/16538 - Ho2S Circuit No Activity Detected (Bank 2, Sensor 1)

1996 Audi A4 Base, StandardSECTION DTC P0154/16538 - Ho2S Circuit No Activity Detected (Bank 2, Sensor 1)
NOTE: DTC is set when signal voltage is 370-430 mV for more than 4 seconds, 123 seconds after engine start with coolant temperature more than 86°F (30°C).
  1. Inspect Heated Oxygen Sensor (HO2S) connector for looseness and/or corrosion. HO2S is located on driver side of vehicle before 3-way catalytic converter. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle.
  2. Turn ignition off. Disconnect HO2S connector. Using a DVOM, check continuity between HO2S connector (sensor side) terminal No. 4 and engine ground. If continuity is present, go to next step. If continuity is not present, replace HO2S. Erase DTC memory and test drive vehicle.
  3. Turn ignition on. Using a DVOM, check voltage between HO2S connector (harness side) terminal No. 4 and engine ground. Voltage should be 350-450 mV. If voltage is within specification, circuit is okay. Erase DTC memory and test drive vehicle. If voltage is not within specification, go to next step.
  4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
  5. Using DVOM, check resistance between HO2S connector (harness side) terminal No. 4 and test box socket A21. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
  6. Repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING  in this article.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.