Why is EGR not needed at engine idle?
Why is EGR not needed at engine idle?
This feature reduces or eliminate engine ping caused by early detonation. This function is not needed at engine idle or when the vehicle is cold. This is why the EGR system is quite complicated and receives many inputs from other sensors that facilitate its operation.
Why does O2 sensor drift rich during EGR flow?
Pre-OBD2 GM vehicles will watch O2 sensor activity while the ECM is commanding EGR flow, because O2 sensor readings will drift slightly rich when EGR is flowing due to the displacement of oxygen by the inert exhaust gas entering the intake.
What’s the diagnostic code for the EGR valve?
Several technical service bulletins for a wide variety of different makes and models have documented different problems associated with the EGR valve system. With some exhaust gas issues you might set a diagnostic trouble code of PO401 or P0402.
Why is EGR important to the p0401 code?
Usually on an OBD2 system that sets the P0401, the ECM/PCM must see the failure on two consecutive trips before it will permanently set the code and trigger the Check Engine Light. The EGR system is important because it reduces emissions by allowing burnt exhaust gas to flow back into the engine.
What to do if your EGR valve is blocked?
When the EGR valve is blocked, error codes of P1404 and P1406 may display on the engine light area. Remove the plug and clean it using the valve cleaning kit to remove blockages.
Usually on an OBD2 system that sets the P0401, the ECM/PCM must see the failure on two consecutive trips before it will permanently set the code and trigger the Check Engine Light. The EGR system is important because it reduces emissions by allowing burnt exhaust gas to flow back into the engine.
How does an EGR valve work on a diesel engine?
When you slowly and efficiently come to a stop, the valve also closes and stops the flow of exhaust gases. The process continues so long as the engine is operating. Once you shut off the engine, the valve also closes and stays in that position. Diesel and gasoline-powered engines can use an array of EGR valve configurations.
Pre-OBD2 GM vehicles will watch O2 sensor activity while the ECM is commanding EGR flow, because O2 sensor readings will drift slightly rich when EGR is flowing due to the displacement of oxygen by the inert exhaust gas entering the intake.
