Posted: 12/21/2010 7:04:01 AM EDT
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2003 Ford F-150 4.6 4X4 Automatic
64,000 miles Service engine soon light came on. AutoZone pulled code P0405 regarding EGR Circuit I replaced the EGR valve and the EGR sensor, then reset the code by unhooking the battery. Light came back on 350 miles later (today). I replaced the only two items in that system, what should I look at next? I just bought this truck and haven’t even made one payment yet. I’m just sick about this. I appreciate any help you may be able to offer. Thanks, Matt EDIT When I got home tonight I took the vacuum line off the top of the EGR valve and used a hand pump to open the diaphragm inside. The engine bogged as it should thus eliminating a blockage in the hard pipe and from the manifold and the ports in the intake manifold. I also confirmed that the two rubber lines that diverge off the manifold to EGR pipe are secure and not leaking. I also confirmed that there is not an overpressure coming out of these lines with a pressure gauge. This eliminated a blockage in the exhaust. In fact, my pressure is so low that it only makes the needle in my gauge twitch, not rise to a consistent measurable level, but there is definitely some exhaust coming out. I also checked the supply vacuum to the little solenoid that actually opens the EGR and it was good. But, I have no way to confirm that the solenoid is working properly. Can you advise how to make this check? EDIT Since the only item left to replace in the EGR system was the EGR Solenoid that activates the EGR valve I went ahead and replaced it today and reset the code again. While I had the hood up I pulled off the two hoses that run to the DPFE sensor and revved the engine a bit to confirm there were no blockages. I had quite a bit of moisture spit out of the hoses when I did this. Could moisture in the DPFE be causing my trouble code P0405? |
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You are going to need to take the throttle body off.
Inside of the casting of the throttle body are two small ports which run exhaust gases back into the intake after the butterfly. These will be plugged solid with carbon. Your kicking the Differential Pressure out of range because the DPFE sensor is not seeing the pressure drop after the EGR is opened to recirculate. The AR-15 Gas Tube Cleaner and some carb clean spray will clean them right up. Just make sure to get the entire length of passage cleaned out (blow through it afterward_ Sorry but that the problem with Piggly Wiggly auto parts and going off "codes", you ended up shooting the messenger by replacing the DPFE and EGR where the new DPFE is telling you exactly the same thing. |
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You are going to need to take the throttle body off. Inside of the casting of the throttle body are two small ports which run exhaust gases back into the intake after the butterfly. These will be plugged solid with carbon. Your kicking the Differential Pressure out of range because the DPFE sensor is not seeing the pressure drop after the EGR is opened to recirculate. The AR-15 Gas Tube Cleaner and some carb clean spray will clean them right up. Just make sure to get the entire length of passage cleaned out (blow through it afterward_ Sorry but that the problem with Piggly Wiggly auto parts and going off "codes", you ended up shooting the messenger by replacing the DPFE and EGR where the new DPFE is telling you exactly the same thing. When I got home tonight I took the vacuum line off the top of the EGR valve and used a hand pump to open the diaphragm inside. The engine bogged as it should thus eliminating a blockage in the hard pipe from the manifold and the ports in the throttle body. I also confirmed that the two rubber lines that diverge off the manifold to EGR pipe are secure and not leaking. I also confirmed that there is not an overpressure coming out of these lines with a pressure gauge. This eliminated a blockage in the exhaust. In fact, my pressure is so low that it only makes the needle in my gauge twitch, not rise to a consistent measurable level, but there is definitely some exhaust coming out. I also checked the supply vacuum to the little solenoid that actually opens the EGR and it was good. But, I have no way to confirm that the solenoid is working properly. Can you advise how to make this check? |
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What brand DPFE did you use? Please tell me it's a Motorcraft. Nope, I got it from Autozone. The Ford stealership was closed on Sunday. I need to scrounge up a detail on what the electrical values should be on the connector so I can check it with my meter. |
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From the PCED. One wire is ground, one is 5 volt reference, and the third is the signals indicated here. KOEO Hot Idle 30 MPH 55 MPH DPFEGR .25-1.30 .25-1.30 .25-4.65 .25-4.65 DCV Thanks for the details. Did you happen to read the update in my original post? I'd like to be able to check the vacuum operated solenoid that opens the EGR valve. |
| There can also be a vacuum leak elsewhere in the system that can trigger an EGR code. I have a 98 with the 4.6 that had this problem. My vacuum "leak" (read: someone had unplugged a couple connections) was in the main vacuum bundle on the passenger side that also feeds the vent control settings. The engine appeared to be running fine, but the EGR code kept coming back. While in my case it was the fault of a mechanic, you might have a cracked vacuum line somewhere contributing to your problem. |
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From the PCED. One wire is ground, one is 5 volt reference, and the third is the signals indicated here. KOEO Hot Idle 30 MPH 55 MPH DPFEGR .25-1.30 .25-1.30 .25-4.65 .25-4.65 DCV Thanks for the details. Did you happen to read the update in my original post? I'd like to be able to check the vacuum operated solenoid that opens the EGR valve. No, dude, you're going in the wrong direction. P0405 is a circuit fault in the dpfe circuit. It fell below 0.2 volts during operation. P0401 is a low flow code, and could be caused by the valve, solenoid, clogged ports, or lines. You are looking at the dpfe, wiring and pcm only. You need to back probe the pcm pin for the dpfe and drive to duplicate the concern. Moisture in the dpfe hoses is totally normal, it is just condensation from the exhaust like what comes out the tailpipe. when the engine gets hot, it goes away. |
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From the PCED. One wire is ground, one is 5 volt reference, and the third is the signals indicated here. KOEO Hot Idle 30 MPH 55 MPH DPFEGR .25-1.30 .25-1.30 .25-4.65 .25-4.65 DCV Thanks for the details. Did you happen to read the update in my original post? I'd like to be able to check the vacuum operated solenoid that opens the EGR valve. No, dude, you're going in the wrong direction. P0405 is a circuit fault in the dpfe circuit. It fell below 0.2 volts during operation. P0401 is a low flow code, and could be caused by the valve, solenoid, clogged ports, or lines. You are looking at the dpfe, wiring and pcm only. You need to back probe the pcm pin for the dpfe and drive to duplicate the concern. Moisture in the dpfe hoses is totally normal, it is just condensation from the exhaust like what comes out the tailpipe. when the engine gets hot, it goes away. OK man, I'm going to break out the meter and work on it this weekend. I'll keep you posted on my progress. Thanks for the help, have a good Holiday. |