Last week my check engine light came on. After doing the ignition trick, it displayed the code P0404 and I ordered an EGR valve. It arrived yesterday and before I could install it (was going to do it this weekend), the check engine light went out. Should I replace it anyway? Or should I hold onto the new part and see if the light comes back on. Anyone else experience this? I have a '08 2 door X.

 

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Here is some information for the code you have.
EGR Codes usually end up being fixed by changing the EGR valve.
Since your light went out, I would wait to see if it comes back on.
If it comes back on, you can troubleshoot the possible causes, or just change the valve.
I don't make a habit of changing parts first, but people's experiences on the forum indicate changing the valve is the best bet.


P0404-EGR POSITION SENSOR RATIONALITY OPEN


Theory of Operation


The EGR valve has a position sensor and the EGR position rationality is designed to make sure that the valve moves freely within its operating range. Closed valve position reference check verifies that the valve is within its allowable upper and lower limits. The EGR position rationality test looks for a sustained error relative to commanded valve position.

• When Monitored: Engine running.
• Set Condition: The EGR flow or valve movement is not what is expected. A rationality error has been detected fro the EGR Close Position Performance. Two trip fault.

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[TD="bgcolor: white"]EXCESSIVE RESISTANCE IN THEEGR SENSOR SIGNAL CIRCUIT
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[TD="bgcolor: white"]EXCESSIVE RESISTANCE IN THE 5 VOLT SUPPLY CIRCUIT
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[TD="bgcolor: white"]EXCESSIVE RESISTANCE IN THE EGR SOLENOID CONTROL CIRCUIT
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[TD="bgcolor: white"](K900) SENSOR GROUND CIRCUIT OPEN
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[TD="bgcolor: white"](Z906) EGR SOLENOID GROUND CIRCUIT OPEN
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[TD="bgcolor: white"]POWERTRAIN CONTROL MODULE [/TD]
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My 2008 did the same. On/off 3 or 4 times before I just replaced the EGR and ended the problem. I'd go ahead and install.

 

Thanks! I may hold off a little just let my father finish putting his F350 back together first so he can tow with it again, unless the light comes back on again. He usually helps me work on my vehicles (past/present).

 

Light came back on, although this time before it came on, I noticed a slight engine hesitation while coming to a stop. Before I didn't have that. Anyway, I will definitely be replacing the valve now. Just for kicks I did the ignition trick again and it displayed the same code.

 

I have a 08 rubicon and p404 light came on mine and its the egr valve I replaced mine and no problems since