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Home >> Volvo >> 1993 >> 940 Base, 4D Sedan, AW70L >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Controls - Tests W/Codes) >> Fault Code Testing >> Code 2-3-1 (Lambda Control Rich Or Lean In Part-Load Range) Or Code 2-3-2 (Lambda Control Rich Or Lean At Idle)

Code 2-3-1 (Lambda Control Rich Or Lean In Part-Load Range) Or Code 2-3-2 (Lambda Control Rich Or Lean At Idle)

WARNING: This page is about a different car, the 1994 Volvo 960. However, it is still accessible from the selected car via links, so may be relevant.
  1. Control unit receives information from oxygen sensor on whether fuel/air mixture is too rich or too lean in part-load and idling ranges. Control unit adaptive system compensates for this by making mixture leaner or richer as necessary. If mixture must be compensated excessively, a fault code is set.
  2. Start engine. Connect voltmeter between terminals No. 1 and 2 in starter motor 2-pin connector. Voltmeter should indicate battery voltage. If no voltage is present, check fuse No. 30.
  3. Stop engine. Disconnect starter motor connector. Connect ohmmeter between starter motor connector terminals No. 1 and 2. Ohmmeter should show 3-13 ohms, depending on resistor temperature.
  4. Connect Measuring Unit (999-3070 ) to ECU. See CONNECTING MEASURING UNIT TO ECU  . Start engine. Connect voltmeter between measuring unit terminals No. 28 and 30. After a short interval, voltmeter should oscillate between 0.1-1.0 volt.
  5. If voltage remains constant at zero volts, sensor is interpreting fuel/air mixture as lean. If voltage is constant at one volt, sensor is interpreting fuel/air mixture as rich.
  6. If either fault code 2-3-1 or 2-3-2 is displayed and voltmeter is oscillating between 0.1-1.0 volt, Lambda control is correctly adjusting CO content even though ECU is indicating fault.
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