check engine and fuel light on


Asked by Jul 30, 2016 at 10:52 AM about the 2004 Chevrolet Impala LS

Question type: Maintenance & Repair

I have plenty of fuel..n car keep idling low...n then
cut off..had Auto zone read codes off computer
P0401 Insufficient EGR flow detected..
What's wrong with my car??

2 Answers


If the NOx goes down when the EGR valve is raised (this test is most commonly performed on a Dynamometer), it is likely that one or more EGR passages or cylinders are plugged or very restricted, making the EGR only go to one or two cylinders. When this occurs, you may notice misfires and even have misfire codes along with the P0401. This can occur on vehicles that use EGR "runners" for each cylinder. Others can learn from this..In your case I would do a quick check of the MAF and IAC someone who knows what their doing can diagnose and correct this fast.


A P0401 code and bad/rough idle means you have a problem with the EGR valve or it's DPFE sensor. The incorrect fuel reading is likely caused by a bad fuel sending unit (its mounted inside the fuel tank). The fuel sending unit and the EGR circuit are separate things, in other words you have more than one thing wrong with your car.

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