Check engine light keeps coming on (p0401).

Asked by Feb 19, 2014 at 10:04 PM about the 1999 Ford Expedition 4 Dr XLT 4WD SUV

Question type: Maintenance & Repair

Replaced the engine in my 1999 Ford Expedition.   Check Engine light keeps coming on.  
Replaced  the EGR valve, sensor and solenoid...car runs fine...but the check engine light
keeps coming on with the same P0401 code??????

2 Answers

55

check your gas cap if not tightened properly, it may cause check engine light to stay on. or if your gas cap is not that of your vehicle, it will also cause light to engage . you may have to have the comp reset.

2 of 2 people found this helpful.

I also replaced modulator, air intake boot, pcv and grommet and some vacuum lights. I just replaced the gas cap and saw that my gas cap was missing a large plastic cylinder piece from the inside. Cleared code p0401 from my 1998 toyota camry. And hasn't returned so far. But it's only been the morning so far. We will see.

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