GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.0L (L34 GMDAT) 🢒 DTC 013

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

Diagnostic Aids

Normal scan tool voltage varies between 100-999 millivolts while in Closed Loop.

Step

Action

Values

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Connect the scan tool to the data link connector (DLC).
  2. Start the engine.
  3. Run the engine until it reaches operating temperature.
  4. Inspect for Closed Loop operation.

Does the engine control module (ECM) go into Closed Loop?

--

Go to Step 3

Go to Step 8

3
  1. Run the engine until it reaches operating temperature.
  2. Observe the oxygen sensor (O2S) reading at different throttle settings.

Does the scan tool read the oxygen sensor input toggling between the values specified?

100-900 mv

Go to Step 7

Go to Step 4

4
  1. Turn the ignition to LOCK.
  2. Disconnect the O2S connector.
  3. Inspect the O2S pigtail lead at the sensor.

Is the lead properly attached to the sensor?

--

Go to Step 5

Go to Step 9

5
  1. Reconnect the O2S connector.
  2. Start the engine.
  3. Run the engine until it reaches operating temperature.
  4. Make a vacuum leak by disconnecting or partially disconnecting a vacuum hose. Do not disconnect the manifold absolute pressure (MAP) sensor.

Does the oxygen sensor input stay fixed at or below the value specified?

300 mv

Go to Step 6

Go to Step 8

6
  1. Run the engine until it reaches operating temperature.
  2. Make a slight vacuum leak at the MAP sensor vacuum hose connection.

Does the oxygen sensor input stay fixed at or above the value specified?

600 mv

Go to Step 7

Go to Step 8

7
  1. Clear the intermittent DTC 013 from the ECM.
  2. Road test the vehicle.
  3. Perform the Diagnostic System Check.

Did DTC 013 reset in the ECM?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

8
  1. Turn the ignition to LOCK.
  2. Disconnect the O2S connector.
  3. Turn the ignition ON.
  4. Measure the voltage at the O2S connector, ECM side of the connector.

Is the voltage within the value specified?

300-600 mv

Go to Step 9

Go to Step 10

9
  1. Replace the O2S. Refer to DTC P1115 .
  2. Road test the vehicle.
  3. Perform the Diagnostic System Check.

Is the repair complete?

--

System OK

--

10

Inspect for an open or short to ground between the oxygen sensor connector and the ECM connector terminal D9.

Is the problem found?

--

Go to Step 11

Go to Step 12

11
  1. Repair the wire as needed.
  2. Road test the vehicle.
  3. Perform the Diagnostic System Check.

Is the repair complete?

--

System OK

--

12
  1. Replace the ECM. Refer to Engine Control Module Replacement .
  2. Road test the vehicle.
  3. Perform the Diagnostic System Check.

Is the repair complete?

--

System OK

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