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Q: 2009 Ford Escape has a code P0400 even after EGR valve replacement

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I have a 2009 Ford Escape FWD 3.0L V6 with a P0400 EGR flow error P0400. I replaced the EGR valve and the check engine problem went away for about a week. However, the light has come back on with the same P0400 error.

I have performed some of the pinpoint KD: Electric Exhaust Gas Recirculation (EEGR) System tests. Under KD5: Check the EEGR Circuits For a Short to Ground the resistance tested is supposed to be greater than 10 Ohms. My tests show the resistance to be around 5.5 Ohms on pins 1,3,4 and 6 on the EGR harness. In addition under KD7: Check the EEGR circuits for a short to voltage, I am getting around 2.5 Volts on pins 1,3,4, and 6 on the EGR harness..... and I believe the voltage with KOEO should be zero.

I am uncertain what to do next in resolving this issue... any help would be greatly appreciated. Thanks for the help!!

My car has 110000 miles.
My car has an automatic transmission.

If your test results for KD5 and KD7 are accurate, there is a short between the PCM and EGR stepper motor. Your readings indicate both a short to ground and power, so my guess is that the four wires inside the harness are shorting against each other as well as to chassis ground somewhere. You’ll need to trace and visually inspect the wiring harness to determine exactly where the problem is. These test results seem odd, so it might be best to have your check engine light problem diagnosed by a professional, such as one from YourMechanic.

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