Engine missing, P0401 code
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Junior User
Joined: Jul 2006
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Engine missing, P0401 code
I have a 2001 ranger 4.0L 4x4 4door automatic trans ranger that had been missing or stumbling for 2 weeks. It all started after I changed spark plugs with Napa replacement Autolites but this could be all coincidence because the roads were icy and really rough for months and it was impossible to tell. The plug wires look good, and vacuum lines are hooked up and also look good. I also wiggled sensor wire connectors to see if it helped but it didn't.
It idles and under WOT is fine, but when im under light to medium acceleration I notice stumbling and jerking at my preferred power range. Also, this happens even when the truck is cold and driving away, and is more pronounced when the engine warms up. Would the DPFE sensor cause this? It took 2 weeks of driving before the check engine light to display, and the code P0401. Also, should have I put dielectric grease in the spark plug boots?
It idles and under WOT is fine, but when im under light to medium acceleration I notice stumbling and jerking at my preferred power range. Also, this happens even when the truck is cold and driving away, and is more pronounced when the engine warms up. Would the DPFE sensor cause this? It took 2 weeks of driving before the check engine light to display, and the code P0401. Also, should have I put dielectric grease in the spark plug boots?
Senior User
Joined: Oct 2004
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P0401 - Insufficient EGR flow.
Check your EGR valve to make sure it's not stuck shut, and the port running into it from the exhaust side to make sure it's open and not plugged. There's a vacuum line running to it at the opposite end from the plunger, check that it's connected and not cracked/split and that vacuum applied to the diaphragm at the nipple (or the hose if still connected to the valve) makes the plunger rise to open the valve and thus open the port. BUT - before you replace the EGR valve, inspect the DPFE/EGR Valve Pressure Feedback Sensor and hoses. It's common for a bad DPFE sensor to throw a CEL.
Check your EGR valve to make sure it's not stuck shut, and the port running into it from the exhaust side to make sure it's open and not plugged. There's a vacuum line running to it at the opposite end from the plunger, check that it's connected and not cracked/split and that vacuum applied to the diaphragm at the nipple (or the hose if still connected to the valve) makes the plunger rise to open the valve and thus open the port. BUT - before you replace the EGR valve, inspect the DPFE/EGR Valve Pressure Feedback Sensor and hoses. It's common for a bad DPFE sensor to throw a CEL.
New User
Joined: Mar 2003
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From: Pearland, TX
I also have a 2001 Ranger 4.0 which is giving the P0401 code. I replaced the egr valve to no avail. The DPFE is rather small on this year model. Appears half the size as posted on another thread. Part # on unit is YF1E-9J460-AD. All the vacuum hose and other lines appear good. Should replacing this solve the problem?
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Joined: Sep 2008
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As I just posted on another thread, I had same exact code on my '97 ranger. I replaced the dpfe sensor. problem solved. On my truck, its located to the right of the intake man. Looks like a matchbox, only bigger. Has a electrical connector on its right w/ 2 small exhaust lines coming out the bottom. Very simple to replace.
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