GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.0L (L34 GMDAT) 🢒 DTC 013, 044, or 045

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC 013: O2S Circuit Insufficient Activity Sensor 1

DTC 044: O2S Circuit Low Voltage Sensor 1

DTC 045: O2S Circuit High Voltage Sensor 1

Circuit Description

The electronic control module (ECM) supplies a voltage of about 450 millivolts between the ECM terminals D9 and C9. The oxygen sensor (O2S) varies the voltage within a range of about 1 volt if the exhaust is rich, down to about 100 millivolts if the exhaust is lean. The O2S is like an open circuit and produces no voltage when it is below 360°C (600°F). An open O2S circuit or a cold O2S causes Open Loop operation.

Conditions for Setting the DTC

013

    • DTCs 021,022, 033, 034 are not set.
    • The engine has been running for at least 60 seconds.
    • The throttle angle is above 5 percent.
    • The coolant temperature is above 70°C (158°F).
    • The O2S voltage is between 340-550 millivolts.
    • The DTC runs continuously when the above conditions are met for 20 seconds.

044

    • DTCs 021,022, 033, 034 are not set.
    • The engine has been running for at least 60 seconds.
    • The throttle angle is above 5 percent.
    • The coolant temperature is above 70°C (158°F).
    • The O2S voltage is less than 274 millivolts.
    • The DTC runs continuously when the above conditions are met for 40 seconds.

045

    • DTCs 021,022, 033, 034 are not set.
    • The engine has been running for at least 60 seconds.
    • The throttle angle is above 5 percent.
    • The coolant temperature is above 70°C (158°F).
    • The O2S voltage is more than 865 millivolts.
    • The DTC runs continuously when the above conditions are met for 10 seconds.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

With the engine running, observe the O2S voltage parameter. The reading should fluctuate above and below the range of 350-550 mV.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector of the O2S sensor 1.
  2. Ignition ON, verify that the O2S parameter is between 350-500 mV.
    3. ⇒If less than 350 mV, test the signal circuit of the O2S sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
    ⇒If greater than 500 mV, test the signal circuit of the O2S sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

    Important: The test lamp is used to load the circuit and may not illuminate.

  3. Connect a test lamp between the low reference circuit of the O2S sensor and the positive terminal of the battery.
  4. Ignition ON, test for less than 0.1 volt between the low reference circuit of the O2S sensor and the negative terminal of the battery.
    5. ⇒If greater than 0.1 volt, test the low reference circuit of the O2S for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  5. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the O2S sensor and verify the O2S sensor parameter is less than 60 mV.
    6. ⇒If greater than 60 mV, test the signal circuit of the O2S sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM.
  6. Verify that the following conditions do not exist:
    7. • Lean fuel injectors--Refer to Fuel Injector Balance Test with Special Tool .
    • Low fuel system pressure--Refer to Fuel System Diagnosis .
    • Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Exhaust leaks near the O2S.
    • Engine vacuum leaks.
         ⇒If you find any of the above conditions, repair as necessary.
  7. If all circuits/connections test normal, replace the O2S sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Oxygen Sensor Replacement
    •  Control Module References for engine control module replacement, setup, and programming