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Home >> Volvo >> 1993 >> 850 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Trouble Code Testing >> Fuel Injection Diagnosis >> 1-1-3 (HO2S Integrator At Maximum Enrichment Limit), 2-2-1 (Adaptive HO2S Control Rich At Part Load), 2-3-1 (Adaptive HO2S Control Lean At Part Load) & 5-1-2 (HO2S Integrator At Maximum Lean Running Limit)

1-1-3 (HO2S Integrator At Maximum Enrichment Limit), 2-2-1 (Adaptive HO2S Control Rich At Part Load), 2-3-1 (Adaptive HO2S Control Lean At Part Load) & 5-1-2 (HO2S Integrator At Maximum Lean Running Limit)

  1. Code 1-1-3 or 2-2-1 means that engine is running lean. This may be caused by an air leak or an HO2S sensor fault. Code 2-3-1 or 5-1-2 means that engine is running rich. This may be caused by high fuel pressure, leaking injector(s), faulty MAF signal, or faulty HO2S sensor.
  2. Connect measuring unit to fuel injection ECU. See MEASURING UNIT  under SELF-DIAGNOSTIC SYSTEM. To check HO2S sensor signal, start engine. Connect voltmeter between measuring unit terminals No. 22 and 23. Voltage should vary between .1-.9 volt after about 30 seconds.
  3. If voltmeter indicates a constant one or zero volts, HO2S sensor is interpreting lean air/fuel ratio or is shorted to ground. Disconnect HO2S sensor connector at firewall. Use a voltmeter and backprobe between connector terminal No. 2 and ground. See Figure .
  4. If voltage remains constant at zero or one volt, check engine CO adjustment. If voltage varies between .1-.9 volt and code is still present, HO2S control is adjusting CO correctly but fuel injection ECU is indicating fault. Check engine CO.
  5. To check CO, connect CO meter to CO tap in exhaust pipe. Start and run engine to operating temperature. Disconnect HO2S connector. Display, record, then erase codes. Check CO.
  6. If meter indicates low CO and engine operates very unevenly, engine is running lean. See Codes 1-1-3 and 2-2-1. If meter indicates high CO (greater than 2.5 percent), engine is running rich and system must make mixture leaner to compensate for fuel leakage or other fault. See Codes 2-3-1 and 5-1-2.
  7. If CO content is .3-2.5 percent, and engine runs normally, reconnect HO2S sensor and recheck CO content. If reading becomes too high or low, repeat test using new HO2S sensor. If CO content is still incorrect, repeat test using new fuel injection ECU.
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