Power Solutions, Inc.

DTC 212

UnclassifiedElectrical

What This Code Means

HO2S Open/Inactive; DST displays HO2S voltage fixed between 0.4 and 0.5 volts after 2 minutes of idle run time

Possible Causes

  • •No power between HO2S connector heater ground pin D and battery voltage positive
  • •No power between HO2S connector heater power pin C and engine ground
  • •Faulty System Power Relay circuit
  • •No continuity between HO2S sensor connector ground pin A and ECM HO2S sensor ground PIN 49
  • •No continuity between HO2S sensor connector signal pin B and ECM connector HO2S signal pin 55
  • •Damage, corrosion, or contamination on ECM connector pins 49 and 55
  • •Damage, corrosion, or contamination on HO2S connector terminals A, B, C, and D
  • •Faulty HO2S Sensor

Suggested Actions

  1. 1Perform On-Board (OBD) System Check
  2. 2Back probe HO2S wire harness connector and check for voltage between HO2S connector heater ground pin D and battery voltage positive
  3. 3Back probe HO2S wire harness connector and check for voltage between HO2S connector heater power pin C and engine ground
  4. 4Check System Power Relay circuit
  5. 5Check for continuity between HO2S sensor connector ground pin A and ECM HO2S sensor ground PIN 49
  6. 6Check for continuity between HO2S sensor connector signal pin B and ECM connector HO2S signal pin 55
  7. 7Inspect ECM connector pins 49 and 55 for damage, corrosion or contamination
  8. 8Inspect HO2S connector terminals A, B, C and D for damage, corrosion or contamination
  9. 9Repair the circuit as necessary (refer to Wiring Repairs in Engine Electrical)
  10. 10Replace HO2S Sensor

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