CODE on every fuel up
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Elder User
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CODE on every fuel up
I have a 99 f-250 v-10 that everytime I fuel up I get a code. P1406 which is the differential pressure sensor. Why does this code come on as soon as I start the truck after refueling. It deals with the back pressure in the exhaust correct? I have a code reader so I am able to clear the code and check for pending codes and nothing ever shows until the MIL light come on after fueling. Should I look into replacing the gas cap and the sensor or just the sensor? Any suggestions will help. Thanks, Eric
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Elder User
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But it throws the diff. pressure sensor code. unless linked somehow. My gas cap is a quarter turn only cap and doesnt click. Just quarter turn and you can feel it pop into place and it wont go any further.
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The Diferential Pressure Valve is under the hood of the truck and is part of the system that helps maintain pressure on the fuel tank. If that valve is bad, tank pressure will be incorrect and the code is set. Leaving the truck running while refueling will also set it off. The system assumes if the engine is running then the cap is on so when you refuel with the truck running it will see a tank pressure drop and try to maintain correct pressure. If it can't maintain the correct pressure the code will be set. Leaving the fuel cap loose will set a code. A bad fuel cap will set a code too. These are all things to consider..... hope it helps.
Hotshot
Joined: Aug 2002
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From: BC, Canada
It really makes no sense that you get that code right after refueling. It might be just coincidence. I can't think of how they would be related.
A P1406 is a code for the Differential Pressure Feedback EGR sensor. It has nothing to do with the fuel system.
While driving, the EGR monitor commands the EGR valve closed and checks the differential pressure across the EGR orifice. The test fails when the signal from the DPF EGR sensor continues to indicate EGR flow even after the EGR valve is commanded closed.
Possible causes are hoses off the DPFE sensor or more likely a bad sensor. Usually if the sensor is bad you'll also get a P0401 or a P1408 as well though. The hoses go from the EGR pipe to the sensor. They are special high heat hoses. Vacuum hose won't work.
A P1406 is a code for the Differential Pressure Feedback EGR sensor. It has nothing to do with the fuel system.
While driving, the EGR monitor commands the EGR valve closed and checks the differential pressure across the EGR orifice. The test fails when the signal from the DPF EGR sensor continues to indicate EGR flow even after the EGR valve is commanded closed.
Possible causes are hoses off the DPFE sensor or more likely a bad sensor. Usually if the sensor is bad you'll also get a P0401 or a P1408 as well though. The hoses go from the EGR pipe to the sensor. They are special high heat hoses. Vacuum hose won't work.
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Elder User
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If I have a hollow cat could that make the sensor trigger the light? I do have one but it has been just recently that I have been getting code. Cat has been hollow for almost a year. I have heard of these sensors going bad quite often to though. I dont know if I want to replace the sensor if the light will keep coming on due to hollow cat.
Hotshot
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From: BC, Canada
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From: zimmerman minnesota
If your truck was built before 3/6/2000 you should have the screw on cap if it was built after you should have the 1/8 turn cap
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Mountain Pass
Joined: Jan 2004
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From: Ixonia, WI
I heard the DPFE sensors were notorious for going bad on the 99 model year vehicles. Mine went out at about 80K and I was told they changed the design on the replacements. The new one did look quite a bit different than the old one physically. I got a P0401 like Racerguy said, now I havent had a code for about 25K. I'm guessin it's a coincidence and the sensor is bad but I could be wrong. Mine was about $50 at the local stealership. good luck