GM tech MW. Labor a question. Problem on my 2001 Pontiac Grand Prix check engine light OBD scan code p1404 was pulled. Replaced the EGR valve, but code came back. Any ideas much appreciated on how to fix this problem. Why does my car have this issue.
MW: If the replacement of the valve did not correct your condition, then you need to have the computer(pcm) re-programmed with a software update. The update fixes a pintle position problem that the pcm expects to see, but does not. This must be done with a dealer scanner. Expect to pay 1 hr. Labor for this re-program.
Or the EGR passage is plugged with carbon and needs to be cleaned. The passage runs from under the valve, into the upper intake manifold. Removal of the throttle body to access the passage is needed. Use a pick or stiff wire to open up the passage.
Basic EGR system description and operation: The exhaust gas recirculation (EGR) system is used to lower oxides of nitrogen (NOx) emission levels caused by high combustion temperature. It does this by decreasing combustion temperature.
The main element of the system is the EGR valve. The EGR valve feeds small amounts of exhaust gas back into the combustion chamber. With the fuel/air mixture thus diluted, combustion temperatures are reduced.
If a problem with the EGR system will not allow the PCM to control pintle position properly, DTC P0404 should set. The PCM also tests for EGR flow. If incorrect flow is detected, DTC P0401 should set. See DTC list for other EGR codes.
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