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2000 Mazda B3000 P0401 issue


July 26, 2011
Reaction score
City, State
Orlando, FL
Year, Model & Trim Level
2000 Mazda B3000
Went to the parts store so I could get my truck scanned and got a P0401 EGR Flow Insufficient. I have a 2000 Mazda B3000 so far I've replaced the DPFE sensor, EGR Valve, and the EGR solenoid. Everytime I replace a part I clear the code and itll come back on after a day.

Right now im going to take the intake upper plenum off and clean out the orifice from the EGR valve to the TB with TB cleaner. While I have this off, is there anything else I could be doing related to this issue that I may have overlooked? Any advice is appreciated so thank you in advance.

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I would suspect a vacuum leak either in the vacuum line that goes to the EGR, or in the DPFE sensor circuit.

I just finished cleaning out the intake plenum. Thanks for the info on the vacuum line McCormack I overlooked that as a possibility. No vacuum to the egr valve and its not going to work, even if the solenoid is working properly. If not a vacuum then I will check the connections and voltages with a VOM.

Reset the code and after driving about 5 miles it came up again. Im going to check the electrical connections at the dpfe sensor and the solenoid. Ive got to search for the specs on the where the voltage should be.

There have been reports here on the boards of DPFE sensors going bad shortly after being replaced, so it's not out of the realm of possibility that your replacement DPFE either went bad again, or else was defective from the factory.

Thanks rwenzing very useful information.

No problem.

Be sure to check the steel EGR tube for rust through and check the special hi-temp DPFE hoses for cracks. Aftermarket DPFE's are known to fail even more quickly than OE.

I noticed I had the Hi temp DPFE hoses swapped in the wrong place. After reading the Tomco Tech tips I figured that out. I havent driven her much in the past couple days but no CEL so far. Thanks again

11 days later and about three hundred miles with no check engine light. Thanks for the help hopefully the light stays off.

Problem solved thanks for the help