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Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: GMC
Satisfied Customers: 3636
Experience:  Owner at Carolina Auto Service &Sales , 20 years Experience in Foreign & Domestic vehicles
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Cam, im getting a p0406. I installed a new egr valve but

Customer Question

Hey cam, im getting a p0406. I installed a new egr valve but code is still there. Gives message "engine power is reduced"
Submitted: 12 months ago.
Category: GMC
Expert:  Chad Farhat replied 12 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 12 months ago.

did you clean the egr passages ?

what is the mileage on it ?

was the below testing performed ?

we need to clean the egr passages & check for power to it ?

2011 GMC Truck Sierra 2500 2WD V8-6.6L DSL Turbo

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DTC P0405 or P0406 Diagnostic Instructions * Perform the Diagnostic System Check - Vehicle ( See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic System Check - Vehicle) prior to using this diagnostic procedure. * Review Strategy Based Diagnosis ( See: Vehicle > Initial Inspection and Diagnostic Overview > Strategy Based Diagnosis) for an overview of the diagnostic approach. * Diagnostic Procedure Instructions ( See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic Procedure Instructions) provide an overview of each diagnostic category. DTC Descriptors DTC P0405 - Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage DTC P0406 - Exhaust Gas Recirculation (EGR) Position Sensor Circuit High Voltage Diagnostic Fault Information

Circuit/System Description The engine control module (ECM) uses the exhaust gas recirculation (EGR) position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5 V reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit. Conditions for Running the DTC * Engine speed is greater than 600 RPM for 10 s. * The DTCs run continuously when the above conditions are met. Conditions for Setting the DTC P0405 The ECM detects that the EGR position sensor voltage is less than 0.25 V for greater than 5 s. P0406 The ECM detects that the EGR position sensor voltage is greater than 4.8 V for greater than 5 s. Action Taken When the DTC Sets * DTCs P0405 and P0406 are Type A DTCs. * The driver information center, if equipped, may display Reduced Engine Power message. Conditions for Clearing the DTC DTCs P0405 and P0406 are Type A DTCs. Reference Information Schematic Reference Engine Controls Schematics ( See: Powertrain Management > Electrical > Engine Controls Schematics) Connector End View Reference Component Connector End Views ( See: Vehicle > Connector Views > Connector End Views By Name) Electrical Information Reference * Circuit Testing ( See: Vehicle > Component Tests and General Diagnostics > Circuit Testing) * Connector Repairs ( See: Vehicle > Component Tests and General Diagnostics > Connector Repairs) * Testing for Intermittent Conditions and Poor Connections ( See: Vehicle > Component Tests and General Diagnostics > Testing for Intermittent Conditions and Poor Connections) * Wiring Repairs ( See: Vehicle > Component Tests and General Diagnostics > Wiring Repairs) DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions ( See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Powertrain Diagnostic Trouble Code (DTC) Type Definitions) Scan Tool Reference Control Module References ( See: Vehicle > Programming and Relearning > Control Module References) for scan tool information Circuit/System Verification 1. Ignition ON, observe the scan tool Desired EGR Position and the EGR Position Sensor parameters. Command the EGR valve from 0 to 40 % with a scan tool. The parameters should increment and remain within 3 % throughout the commanded range. 2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Circuit/System Testing 1. Ignition OFF, disconnect the harness connector at the Q14 EGR Valve. 2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the low reference circuit terminal 3 and ground. ◊If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM. 3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground. ◊If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM. ◊If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM. 4. Ignition ON, verify that the scan tool EGR Position Sensor parameter is greater than 4.8 V. ◊If the parameter is less than the specified range, test the signal circuit for a short to ground. If the circuits test normal, replace the K20 ECM. 5. Ignition ON, install a 3 A fused jumper wire between the low reference circuit terminal 3 and the signal circuit terminal 5. Verify the scan tool EGR Position Sensor parameter is less than 0.25 V. ◊If the EGR Position Sensor parameter is greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM. 6. If all circuits test normal, test or replace the Q14 EGR Valve. Component Testing Ignition OFF, remove the Q14 EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement (LGH) ( See: EGR Valve > Removal and Replacement > Exhaust Gas Recirculation Valve Replacement (LGH))Exhaust Gas Recirculation Valve Replacement (LML) ( See: EGR Valve > Removal and Replacement > Exhaust Gas Recirculation Valve Replacement (LML)). Inspect the Q14 EGR valve for the following conditions: * A sticking, binding or frozen EGR valve * Any coking, soot build up, debris or damage that can cause the EGR valve to stick partially open or closed ◊If a condition is found, clean or replace the Q14 EGR Valve as necessary. Repair Instructions Perform the Diagnostic Repair Verification ( See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests > Diagnostic Repair Verification) after completing the diagnostic procedure. * Exhaust Gas Recirculation Valve Replacement (LGH) ( See: EGR Valve > Removal and Replacement > Exhaust Gas Recirculation Valve Replacement (LGH))Exhaust Gas Recirculation Valve Replacement (LML) ( See: EGR Valve > Removal and Replacement > Exhaust Gas Recirculation Valve Replacement (LML)) * Control Module References ( See: Vehicle > Programming and Relearning > Control Module References) for ECM replacement, setup and programming

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Chad Farhat
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Expert:  Chad Farhat replied 12 months ago.

Specs & dtc info on p0406