DTC P049D - LNP or LNQ
Diagnostic Instructions
DTC Descriptor
DTC P049D 00: Exhaust Gas Recirculation (EGR) Position Not Learnt
Circuit/System Description
The offset of the exhaust gas recirculation (EGR) valve is checked after the offset learning has been completed in after run/post drive. The difference between the maximum and minimum EGR valve offset values is calculated by the engine control module (ECM). If the difference is above a calibrated threshold or the offset learnt value is not within a calibrated range, a fault is recognised. While the offset learning is active, the EGR valve is checked for a jammed valve. If the valve is stuck during opening or closing for a calibrated time, a fault is reported. If either of these conditions occur, the DTC will be set.
Conditions for Running the DTC
| • | DTC P0404 00, P0405 00, P0406 00, or P1407 00 are not set. |
| • | The ignition is OFF and the engine is in after-run/post drive. |
| • | The EGR Valve offset learning procedure is active or complete for current drive cycle. |
| • | The engine coolant temperature (ECT) is between 5-123°C (41-253°F). |
| • | Battery voltage is greater than 10 V. |
| • | These DTCs run continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The ECM detects that the difference between the minimum and maximum EGR valve learnt offset values is greater than 30%. |
| • | The ECM detects that the offset learnt value for the EGR valve is not within a calibrated range. |
| • | The ECM detects a jammed EGR valve during opening or closing the valve for greater than 5 s. |
Action Taken When the DTC Sets
DTCs P049D 00 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P049D 00 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Note: Occasionally, when using an EGR device control, engine reduced power and clean exhaust filter messages may occur after a short delay when commanding large EGR positions. The messages are a result of ECM protecting hardware during device control mode. No DTCs will be stored and the diesel particulate filter does not need to be service cleaned. Exiting device control will restore normal function.
- Ignition ON, observe the scan tool Desired EGR Position and the EGR Position Sensor parameters. Command the EGR valve from 0-40% with a scan tool. The parameters should respond and remain within 3% throughout the commanded range.
- Engine running command the EGR Valve to 40% with a scan tool, then increase the engine speed to 2 500 RPM. The engine should run rough.
- Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
Circuit/System Testing
Note: Perform the Circuit System Verification before proceeding with Circuit/System Testing.
- Ignition OFF, remove the Q14 Exhaust Gas Recirculation Valve. Refer to Exhaust Gas Recirculation Valve Replacement .
- Inspect the Q14 Exhaust Gas Recirculation Valve for the following conditions:
| • | A sticking, binding, or seized 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, replace the Q14 Exhaust Gas Recirculation Valve. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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| © Copyright Chevrolet. All rights reserved |
