2000 PO401 & PO402 Alarms

first of all let me say that this forum is awesome. i'm absolutely not a car guy or mechanic, but folks on here have helped me repair some items in the past...i replaced both oxygen sensors yesterday that were causing the check engine light to come on. after replacing the two sensors, the check engine light stayed off for a couple hours but came on again. after having it checked, there were two codes that show up. they are PO401 & PO402...these have something to do with the egr flow...any ideas?
Please respond by to email in addition to forum if at all possible...thanks

I don't know the year of your Windstar but the DPFE (EGR flow sensor) are prone to failure in some years. It costs about $50 or so and takes about 10 minutes to replace. (on my 99). Search under DPFE I once wrote a small procedeure to test the DPFE.

What made you think you had O2 sensor problems? Often they are replaced unnecessarily.

I don't know the year of your Windstar but the DPFE (EGR flow sensor) are prone to failure in some years. It costs about $50 or so and takes about 10 minutes to replace. (on my 99). Search under DPFE I once wrote a small procedeure to test the DPFE.

What made you think you had O2 sensor problems? Often they are replaced unnecessarily.

When the engine light first came on i took the van to advance auto parts. it coded for both oxygen sensors.

DPFE is a VERY common failure for the P0401 and P0402 codes.

Whenever you get your codes read....make sure to get the actual numeric code. They don't normally give you that unless you ask for it. Reason being....that most people don't understand the numeric code. There are a LOT of codes relative to the oxygen sensors. If you get P0171 and / or P0174, that is saying that the oxygen sensors are reporting a lean condition. The MOST common cause for that is a vaccum leak....and not the oxygen sensors. Your '99 would fall under the years that need the upper intake manifold bolts replaced as per the TSB. If you do that....also clean the EGR ports....as they are right there...out in the open.

Please post back with any questions...and numeric codes that you might need help with.

I had P0402 several weeks ago - and about a month or two after completing the isolator bolt procedure. At first I was afraid something had gone wrong with my original work - but after dumping the code, realized it was just the DPFE finally going bad. It's an easy replacement (10-15 minutes!). I cleared the code by disconnecting the battery. It has run great (and no CEL) ever since.

Have your dealer run your vin no. for a recall on the DPFE sensor.
Also for recalls or TSB on pcm reflashing to cure some of the problems.
Did you get a recall in the mail?