2011 LML 2500 4wd P040F and P041C

Jeff2500HD

New member
Mar 5, 2019
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I went from Vegas to Ventura California diving. Vegas very hot 110's and dry, Ventura 80's day and 60's night, humid and foggy/misty in the morning. In the morning is when I got the first codes popped, cleared them with my Zurich scanner. Good for a day, then happened again. I thought maybe once back in the hot/dry desert it would stop, but it has continued. It is not consistent, sometimes a day passes, no codes, sometimes it pops when driving for a little, other times it pops as soon as I start it.

P040F Temperature Sensor "A" Circuit High and P041C Temperature Sensor "B" Circuit Low. Drivability does not change at all. I keep my scanner in the truck and just clear it as it pops up. Does this seem like the EGR valve or by pass valves? I am unfamiliar with the valving related to the EGR and what is involved in fixing/swapping them. What are the long term risks of not fixing this right away? I have an assumption that maybe the gasket is old/dried from years in the desert and when things were so damp in California that maybe some moisture got in and did something, now maybe intermittent shorting or something.

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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
Sounds like the egr temp sensor is an issue, not the egr its self. Should be located on the riser that comes off the up pipe behind the egr switching valve. This is back by where your heater hoses are.
 

Jeff2500HD

New member
Mar 5, 2019
3
0
1
Sounds like the egr temp sensor is an issue, not the egr its self. Should be located on the riser that comes off the up pipe behind the egr switching valve. This is back by where your heater hoses are.
Is this a situation where the temp sensors just need swapped out or is there a cleaning process? Any idea what causes this? Soot?
 

Jeff2500HD

New member
Mar 5, 2019
3
0
1
x2
Is this a situation where the temp sensors just need swapped out or is there a cleaning process? Any idea what causes this? Soot?