GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Engine 🢒 Engine Controls - 1.6L (L91) 🢒 DTC P0405

Circuit Description

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve. If the voltage on the signal circuit of the EGR valve position sensor is less than a calibrated value, DTC P0405 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0405 Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage

Conditions for Running the DTC
    • The ignition is ON or the engine is operating.
    • DTC P0405 runs continuously once the above condition is met.

Conditions for Setting the DTC

The ECM detects that the EGR position voltage is less than 0.01 volts for more than 1 second.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will illuminate after 3 consecutive trips with a fail.
    • The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

Conditions for Clearing the MIL/DTC
    • The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault.
    • DTCs can be cleared by using the scan tool.
    • Disconnect the ECM battery feed for more than 10 seconds.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Start the engine.
  2. Allow the engine to idle for 30 seconds.
  3. Observe the DTC Information with a scan tool.

Did DTC P0405 fail this ignition?

--

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the exhaust gas recirculation (EGR) valve.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the EGR Position Sensor parameter with a scan tool.

Is the voltage more then the specified value?

4.9 V

Go to Step 5

Go to Step 9

5

Important: Use a Test Lamp that measures between 25-30 ohms for this test.

Connect a test lamp between the 5-volt reference circuit of the EGR valve position sensor and a good ground.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 6

6

While the test lamp is connected to the 5-volt reference circuit, disconnect the harness connector of the following sensors one at a time:

    • Manifold Absolute Pressure (MAP) sensor
    • Throttle Position (TP) Sensor
    • A/C Pressure Sensor
    • Fuel Level Sensor

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 7

7

Test the 5-volt reference circuit of the following sensors for a short to ground:

    • Manifold Absolute Pressure (MAP) sensor
    • Throttle Position (TP) Sensor
    • A/C Pressure Sensor
    • Fuel Level Sensor

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 8

8

Test the 5-volt reference circuit of the EGR valve position sensor for one of the following conditions:

    • An open
    • High resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

9

Test the signal circuit of the EGR valve position sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

10

Test for an intermittent and poor connection at the EGR valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

11

Test for an intermittent and poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

12

Replace the appropriate sensor. Refer to one of the following procedures:

    • Manifold Absolute Pressure (MAP) sensor--Refer to Manifold Absolute Pressure Sensor Replacement .
    • Throttle Position (TP) Sensor--Refer to Throttle Body Assembly Replacement .
    • A/C Pressure Sensor
    • Fuel Level Sensor

Did you complete the replacement?

--

Go to Step 15

--

13

Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 16

16

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK