Why is my EGR valve stuck in the open position?
One of the most common symptoms of a problem with the vehicle’s EGR valve is a rough idle. It is not uncommon for EGR valves to malfunction and become stuck in the open position. This can lead to exhaust gas recirculation, which causes rough idling even when the conditions are not desirable.
Which is the correct formula for EGR error?
The EGR Error is also normalized for all types of EGR systems. The reading is based on a simple formula: (Actual EGR Position − Commanded EGR) ÷ Commanded EGR = EGR Error. For example, if the EGR valve is commanded open 10% and the EGR valve moves only 5% (5% − 10%) ÷ 10% = −50% error.
Where does the EGR coolant go in a diesel engine?
Pre-turbine (HPL) exhaust is routed via an EGR control valve and an EGR cooler to the engine inlet system. Engine jacket water is used as the cooling medium in the EGR cooler in this example as well. In general, EGR can be cooled with engine coolant, ambient air or a low temperature liquid.
Can a car pass a smog test with a faulty EGR valve?
The EGR valve is an important emissions component, especially for vehicles in states with strict emissions regulations. You won’t be able to pass a smog test with a faulty EGR valve.
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.
How does the ECM know when EGR is flowing?
When EGR is flowing, the pressure will rise in the hose connected below the orifice and drop in the hose connected above it, thus the Engine Controller (ECM/PCM, etc.) can determine if EGR is flowing and how much.
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.
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.