P1406 code

[rocky1961]

I have a 2000 E150 with a 4.6 eng. that started missing randomly like maybe a coil was breaking down or a plug needed replacing. I finally got an engine light after about a month of this and a P1406 differential pressure sensor malfunction is what came up. Anybody out there know how this malfuction could cause a misfire ? Thanks for any help ya'll can offer.

[autojoe]

this sensor measures egr flow.it could cause a lean misfire.they are a common failure items on fords.I would check connector on dpfe sensor since intermittent.clear light and see if comes back on.do you have any testing tools?multimeter?scan tool?hand vacuum pump?not too hard to test this sensor.a scan tool with data stream is nice but could use a multimeter.the vacuum pump you monitor dpfe snesor signal voltage while applying vacuum to sensor.ford redesigned this sensor several times.chances are it is the sensor but could be the circuit also.let me know.

[autojoe]

a misfire would not throw a P1406 code.computer detected a problem with the dpfe circuit.

[autojoe]

the best way for a misfire is to hook a labscope up and look at ignition secondary waveforms.

[rocky1961]

Thanks for your breply, Joe. I will get a chance this coming weekend to locate the sensor and check it out. I do have a multimeter and could check out the sensor . How would I do this?

[autojoe]

testing dpfe circuit would have to be done while fault is evident.if it is an intermittent and when testing it will show good.I would clear code and see if it or how long it takes to show again.....turn on the light.if it is a hard fault it should trigger light right away.you stated that it has a random misfire......how often?under load?engine hot?any other codes?ford has a misfire counter built into mode 6 where you can see if there is any misfires in any cylinder seen by pcm but need a scan tool capable of accessing mode 6.this is very valuable but would have to view while it is actually misfiring.intermittents are the hardest to pinpoint and test.

[autojoe]

I wanted to let you know this code can be caused by a blocked or disconnected dpfe downstream hose......sometimes the dpfe sensor can also plug up.......check downstream hose if plugged or disconnected.
attachment downstream hose.dpfe.jpg

[ASE AMD]

Ur dpfe is probably bad. Changed a ton of them suckers. They will cause misses. Just change it and move on. Best way to check is with scan tool. U look for changes and specific values.