Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
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An exhaust gas recirculation (EGR) system is used in order to lower oxides of nitrogen (NOx) emission levels caused by high combustion temperatures. The EGR accomplishes this by feeding small amounts of exhaust gases back into the combustion chamber. When the air/fuel mixture is diluted with the exhaust gases, combustion temperatures are reduced.
A linear EGR valve is used on this system. The linear EGR valve is designed in order to accurately supply exhaust gases to the engine without the use of intake manifold vacuum. The valve controls exhaust flow going into the intake manifold from the exhaust manifold through an orifice with a control module controlled pintle valve. The control module commands the EGR by applying a 12 volt duty cycle to the EGR valve. This can be monitored on a scan tool as desired EGR position.
The control module can monitor the pintle position with the EGR pintle position signal. This sensor uses a variable resistor with a 5 volt reference, a signal circuit, and a ground. The signal circuit monitors changes in voltage on the variable resistor as the pintle moves.
The VCM will set a DTC P0405 if an unusually low pintle position signal voltage is detected for a calibrated period of time.
No, because the computer applies the 12v as a duty cycle to the EGR valve.
I can email you the complete diagnostic chart for that code or try to upload it.
No, 12 volt is not always present.
Here is the diagnostic chart.
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Do you have a scan tool to access the EGR data in the Vehicle Control Module(VCM)?