Mechanics

CHEVY P0404 & P0403 CODES.....

2000 Chevrolet Impala

Engine Performance problem
2000 Chevy Impala 6 cyl Front Wheel Drive Automatic 120000 miles

I have spent sometime reserching your site (and others) trying to solve the problem....

My car doesn't accelerate/has no power especialy when I'm on HWY. Check engine light showed P0404 first time and after reseting P0403 code)
Don't go any faster when I push the gas pedal down. I have also noticed drop in fuel economy...

Did a tune-up....no changes

Suspect Fuel Pump, O2 sensors or Catalytic Converter....

Please advise....thanks


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Avatar
Iggi71
February 22, 2008.



DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit
Refer to Engine Controls Schematic IAC, Engine Oil Level, Engine Oil Pressure, EGR, EVAP Vent.

Circuit Description
The Powertrain Control Module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM. The linear EGR valve is controlled by using an ignition positive driver and ground circuit within the PCM. The driver has the ability to detect an electrical malfunction in the ignition positive or ground circuit. If an electrical malfunction occurs, the driver signals the PCM to set DTC P0403.

Conditions for Running the DTC
• The engine is cranking or running.

• The system voltage is between 9.0--18.0 volts.

Conditions for Setting the DTC
• The PCM detects an electrical malfunction in the control circuit for the EGR valve.

• The condition is present for more than 20 seconds.

Action Taken When the DTC Sets
• The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC
• The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• The DTC can be cleared by using a scan tool.

Diagnostic Aids
Inspect for the following conditions: Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

• Loose terminal connection

- Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections, and to Connector Repairs in Wiring Systems for diagnosis and repair.

- Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections, and to Connector Repairs in Wiring Systems for diagnosis and repair.

• Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

• Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

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

Listen for an audible click when the solenoid operates. Command the EGR between 0 percent to 10 percent. Repeat the commands as necessary.

This step verifies that the PCM is providing voltage to the solenoid.

This step tests for an open in the ground circuit to the solenoid.

This step tests if voltage is constantly being applied to the solenoid.

The PCM utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

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
Turn ON the ignition, with the engine OFF.
Use a scan tool in order to command the EGR from 0 percent to 10 percent.
Does the solenoid turn ON and OFF with each command?
--
Go to Diagnostic Aids
Go to Step 3

3
Turn OFF the ignition.
Disconnect the EGR.
Turn ON the ignition, with the engine OFF.
Probe the control circuit of the solenoid using a test lamp connected to a good ground.
With a scan tool, command the EGR between 0 percent and 10 percent.
Does the test lamp turn ON and OFF with each command?
--
Go to Step 4
Go to Step 5

4
Connect a test lamp between the control circuit of the solenoid and the ground circuit of the solenoid.
Use a scan tool in order to command the EGR between 0 percent and 10 percent.
Does the test lamp turn ON and OFF with each command?
--
Go to Step 8
Go to Step 10

5
Does the test lamp remain illuminated with each command?
--
Go to Step 7
Go to Step 6

6
Test the control circuit of the solenoid for a short to ground or an open. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 13
Go to Step 9

7
Test the control circuit of the solenoid for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 13
Go to Step 9

8
Inspect for faulty connections at the EGR. 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 13
Go to Step 11

9
Inspect for faulty connections at the PCM. 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 13
Go to Step 12

10
Repair the ground circuit of the solenoid. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?
--
Go to Step 13
--

11
Replace the EGR. Refer to Exhaust Gas Recirculation Valve Replacement.

Did you complete the replacement?
--
Go to Step 13
--

12
Important: The replacement PCM must be programmed.

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

Did you complete the replacement?
--
Go to Step 13
--

13
Use the scan tool in order to record the Failure Records and to clear the DTCs.
Operate the vehicle within the Failure Records conditions.
Does the DTC reset?
--
Go to Step 2
System OK

Dennyp
Feb 22, 2008.
DTC P0404 Exhaust Gas Recirculation (EGR) Open Position Performance
Refer to Engine Controls Schematic IAC, Engine Oil Level, Engine Oil Pressure, EGR, EVAP Vent.

Circuit Description
The Powertrain Control Module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position input in order to ensure that the valve responds properly to commands from the PCM. The PCM compares the actual EGR position with the desired EGR position when the valve is commanded open. If the difference between the actual EGR position and the desired EGR position is more than 15 percent, DTC P0404 will set.

Conditions for Running the DTC
• The ignition is ON.

• The system voltage is between 10.0--18.0 volts.

Conditions for Setting the DTC
• The difference between the actual EGR position and the desired EGR Position is more than 15 percent.

• The condition is present for more than 20 seconds.

Action Taken When the DTC Sets
• The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC
• The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• The DTC can be cleared by using a scan tool.

Diagnostic Aids
Inspect for: • Excessive deposits on the EGR pintle or seat

• Remove the EGR valve and inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

• Loose terminal connection

- Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections, and to Connector Repairs in Wiring Systems for diagnosis and repair.

- Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections, and to Connector Repairs in Wiring Systems for diagnosis and repair.

• Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

• Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

Test Description
Numbers below refer to the step numbers on the Diagnostic Table: Verifies that the malfunction is present.

If DTC P0404 will only set under certain conditions, the malfunction may be intermittent, refer to Diagnostic Aids. If an intermittent wiring problem is not present, check for a poor connection at the PCM or the EGR valve. If the connections are OK and DTC P0404 continues to set, replace the EGR valve.

This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

DTC P0404 - EGR Valve Stuck Closed Step

Action
Value(s)
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.

• DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit

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

Turn ON the ignition switch.
Select the scan tool EGR valve output control function.
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
Review and record scan tool Fail Records data.
Operate the vehicle within Fail Records conditions.
Using a scan tool, monitor Specific DTC info for DTC P0404.
Does the scan tool indicate DTC P0404 failed this ignition?
--
Go to Step 4
Go to Diagnostic Aids

4
Disconnect the EGR valve.
Connect a J 39200 DMM to measure voltage between the EGR pintle position sensor ground circuit and the 5 volt reference A circuit at the EGR valve connector.
Is the voltage at the specified value?
5.0 V
Go to Step 5
Go to Step 10

5
Probe the EGR pintle position signal circuit at the EGR valve harness connector with a J 35616-200 test lamp connected to battery positive voltage.

Did the test lamp illuminate?
--
Go to Step 8
Go to Step 6

6
Connect a jumper between the 5 volt reference A circuit and the EGR pintle position signal circuit at the EGR valve connector.
Observe Actual EGR Position on the scan tool.
Is Actual EGR position at the specified value?
100%
Go to Step 9
Go to Step 7

7
Turn OFF the ignition switch.
Disconnect the PCM.
Test the EGR pintle position signal circuit for an open. Refer to Wiring Repairs.
Did you find and correct the condition?
--
Go to Step 17
Go to Step 15

8
Turn OFF the ignition switch.
Disconnect the PCM.
Probe the EGR pintle position signal circuit with a test lamp to battery positive voltage.
Did the test lamp illuminate?
--
Go to Step 13
Go to Step 14

9
Test for poor terminal connections at the EGR valve. Refer to Testing for Continuity and Testing for Intermittent Conditions and Poor Connections.

Did you find and correct the condition?
--
Go to Step 17
Go to Step 12

10
Inspect for the following conditions: • 5 volt reference A circuit open between the PCM and the EGR valve

• 5 volt reference A circuit shorted to ground

If a problem is found, repair as necessary. Refer to Wiring Repairs.
Did you find and correct the condition?
--
Go to Step 17
Go to Step 11

11
Inspect for the following conditions: • EGR pintle position sensor ground circuit open

• EGR pintle position sensor ground circuit shorted to voltage

If a problem is found, repair as necessary. Refer to Wiring Repairs.
Did you find and correct the condition?
--
Go to Step 17
Go to Step 15

12
Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement.

Did you complete the replacement?
--
Go to Step 17
--

13
Locate and correct the short to ground in the EGR pintle position signal circuit. Refer to Wiring Repairs.

Did you complete the repair?
--
Go to Step 17
--

14
Test the EGR pintle position signal circuit for a short to the EGR pintle position sensor ground circuit.
If a problem is found, repair as necessary. Refer to Wiring Repairs.
Did you find and correct the condition?
--
Go to Step 17
Go to Step 16

15
Test the circuits related to the EGR valve for poor terminal connections at the PCM.
If a problem is found, repair as necessary. Refer to Testing for Continuity and Testing for Intermittent Conditions and Poor Connections.
Did you find and correct the condition?
--
Go to Step 17
Go to Step 16

16
Important: : The replacement PCM must be programmed.

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

Did you complete the replacement?
--
Go to Step 17
--

17
Review and record scan tool Fail Records data.
Clear DTCs.
Operate the vehicle within Fail Records conditions.
Using a scan tool, monitor Specific DTC info for DTC P0404.
Does the scan tool indicate DTC P0404 failed this ignition?
--
Go to Step 2
System OK

Dennyp
Feb 22, 2008.
Problem was solved by changing Cat Converter ($250) in Maineken + Guy spead some cleaner in to the Trottle. Engine on

Before I tried: 1. I have changed Mass Air Flow Sensor. Didn't solve the problem. Put my old sensor back

2. Cleaned EGR valve. Problem was still there

3. Checked Fuel Pump pressure. It was OK

Desided to change Cat Converter. Problem was solved. Now car has so much power. WOW

Tiny
Iggi71
Apr 3, 2008.