1996 Mercury Sable Engine Code

[Hookmaster]

P0401-Exhaust Recirculation Flow Insufficient Detected

How do I troubleshoot this?

[Capt. Don*]

The easiest way is with an NGS tester, you probably don't have one so here is what the code means and a laymans way to diagnose. The code is saying that the voltage on the DPFE sensor is not changing when the EGR valve opens. Three things can cause this, EGR not opening, bad Egr Vacuum Regulator or bad DPFE sensor. If you can get a piece of vacuum hose to fit the port on the EGR valve and with the engine idling in park you can connect to a vacuum pump if available or use your mouth if not and put vacuum to the egr valve, if the engine starts idling poorly or stalls the egr is opening, check vacuum lines fron EVR to EGR if all ok replace the DPFE sensor, Ford base part number 9J460. These have been common failure parts and updated and revised numerous times. Disconnect battey for 15-20 minutes after replacing and light will be out when you restart.

[Scott K]

Most comon would be dpfe sensor!

[Jeremy airjer W]

I pretty much do what capt don said. Most likely a DPFE sensor (dealer only) but I still like to make sure the EGR is working and check the voltages with a scan tool.

[Shack]

I am kind of a late bloomer here, but I will fourth the D.P.F.E. sensor as the possible issue.

They are more common that one would ever think, but when one gets on a D.P.F.E. sensor kick and predicts a D.P.F.E. with out looking at the vehicle, thats when you find out it is something else

Good luck!