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HOMESERVICE MANUALSAUDI1996A4 BASE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - 2.8LCIRCUIT TESTSDTC P0175/16559 - SYSTEM TOO RICH (BANK 2)
1996 Audi A4 Base, Standard

DTC P0175/16559 - System Too Rich (Bank 2)

1996 Audi A4 Base, StandardSECTION DTC P0175/16559 - System Too Rich (Bank 2)
NOTE: DTC is set when HO2S control has dropped below learning limit in lean direction, but HO2S still recognizes mixture is too rich.
  1. Bank 2 identifies fuel injectors on driver side of engine. If DTC P0172/16556 SYSTEM TOO RICH (BANK 1) is also set in memory, this indicates that fuel pressure is too high. Test fuel pressure and residual fuel pressure. See FUEL PRESSURE TEST in BASIC TESTING article. If fuel pressure is okay, go to next step. If fuel pressure was repaired, erase DTC memory and test drive vehicle.
  2. Inspect fuel injectors on driver side of vehicle for poor electrical connection or dirty/clogged injectors. See FUEL INJECTOR TEST in BASIC TESTING article. Repair as necessary. Erase DTC memory and test drive vehicle.
RENDER: 1.0x

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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.