GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P0404 Exhaust Gas Recirculation (EGR) Open Position Performance

Object Number: 602212 Size: SF
Engine Controls Component Views
MAF Sensor, EVAP Components and EGR Valve
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The powertrain control module (PCM) controls the movement of the valve using the exhaust gas recirculation (EGR) control circuit. The PCM monitors the pintle position input to make sure that the valve responds to the commands from the PCM. With the key turned ON, the PCM learns an EGR closed valve pintle position. When the PCM commands the valve closed, the PCM compares the learned closed EGR valve pintle position to the actual EGR position. If the actual EGR position indicates an open valve when the PCM has commanded the valve closed, DTC P0404 will set.

Conditions for Running the DTC
    • System voltage is more than 11 volts.
    • DTC P0401 inactive
    • EGR is enabled

Conditions for Setting the DTC

The actual EGR position is 20 percent less than the desired EGR position.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.
    • The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC
    • The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.
    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions .

Check for excessive deposits on the EGR pintle or seat. Deposits may interfere with the EGR valve pintle extending completely. Deposits in the pintle seat area may cause the pintle to stick.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Verifies that the malfunction is present.

    2.

  2. Attempts to duplicate the malfunction using the stored failure conditions.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: If any of the following DTCs are set, diagnose the other DTC first.

  1. Turn ON the ignition, with the engine OFF.
  2. Select the scan tool EGR valve output control function.
  3. Increment the EGR valve through all positions while comparing desired EGR position to actual EGR position.

Does desired EGR position remain close to actual EGR position at all commanded positions?

--

Go to Step 3

Go to Step 4

3

  1. Review and record scan tool Fail Records Data.
  2. Operate the vehicle within Fail Records conditions.
  3. With a scan tool, monitor the Specific DTC information for DTC P0404 until the test runs.

Does the scan tool indicate DTC P0404 failed last test?

--

Go to Step 4

Go to Diagnostic Aids

4
  1. Turn OFF the ignition.
  2. Disconnect the EGR valve connector.
  3. Turn ON the ignition.
  4. Connect test lamp between the EGR valve control and the EGR valve ground circuits.
  5. With the scan tool, command the EGR to the specified value?

Is the test lamp ON?

100%

Go to Step 5

Go to Step 7

5
  1. Leave the ignition ON, with the engine OFF.
  2. Connect test lamp between the B+ and the EGR pintle position ground circuits.

Is the test lamp ON?

--

Go to Step 6

Go to Step 8

6
  1. Leave the ignition ON, with the engine OFF.
  2. Connect test lamp to battery positive voltage.
  3. Probe the EGR pintle position signal in the harness connector.

Does the scan tool indicate EGR near the specified value?

100%

Go to Step 10

Go to Step 9

7
  1. Turn OFF the ignition.
  2. Disconnect the PCM connectors. Refer to Powertrain Control Module Replacement/Programming .
  3. Test for the following conditions:
    4. • An open or short to ground in the EGR valve control circuit
    • An open in the EGR valve ground circuit
    • Poor connections at the PCM
  4. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

8
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2. Refer to Powertrain Control Module Replacement/Programming .
  3. Test for the following conditions:
    4. • An open EGR pintle position ground circuit
    • Poor connections at the PCM
  4. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

9
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector.
  3. Test the EGR pintle position signal circuit for the following conditions:
    4. • A short to voltage or the 5V reference circuit
    • Poor connections at the PCM
  4. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10
  1. Inspect for poor connections at the EGR valve.
  2. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

11

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

Is the action complete?

--

Go to Step 13

--

12

Important:: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 13

--

13
  1. Review and record scan tool Fail Records data.
  2. Clear DTCs.
  3. Operate the vehicle within the parameters listed in the Conditions for Running the DTC.
  4. With a scan tool, monitor the Specific DTC information for DTC P0404 until the test runs.

Does the scan tool indicate DTC P0404 passed?

--

System OK

Go to Step 2