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Ford Taurus P401 and P402 codes


jeff67's Avatar
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06-16-03, 03:20 PM   #1  
Ford Taurus P401 and P402 codes

The car is a 1997 Ford Taurus G, 3.0L, 89,000 miles.

A few days ago the service engine light came on and the code it gave me was a P0402 (excessive EGR flow detected). I cleared the code several times and it always comes back. Today, the light came on again but it gave me a code P0401 (insufficient EGR flow detected) AND code P0402.

I need some help on troubleshooting this.

The engine always runs smooth at idle or anytime while driving, just as it did before the light ever came on.

The service engine light always comes on just after starting the car. Is this when the code is set or is it set on the previous trip but doesnt show up until the car is restarted?

Thanks

 
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06-16-03, 03:26 PM   #2  
Joe_F
You could have a bad EGR valve or sensor. See what autolibrary.org has to say.

 
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06-17-03, 08:06 PM   #3  
I don't have a solution for you, but beware, when this happened on a 96 Ford Ranger, replacing the DPFE sensor did not solve the problem.

 
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06-17-03, 09:11 PM   #4  
What is sounds like is the egr valve itself is sticking in different positions. It wouldn't hurt to take it off, look for carbon build up on the pintle, and look for carbon build up in the passages also.
This is pretty common on fords. If you clean and or replace the egr, and the insufficient code comes back, you may have to remove the throttle body, and manually clean the passages of the carbon build up..

 
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06-17-03, 10:36 PM   #5  
Thanks for the advice. Lugnut, were you able to solve the problem? I thought it might be the DPFE sensor but maybe it isn't.

I was thinking the EGR valve might be sticking, but if it was sticking, wouldn't the engine idle rough? Or could it be recirculating just enough exaust gas to set the code but not cause a rough idle?

I reset the computer a few more times and only the P0402 code keeps coming back. The P0401 code showed up only once.

 
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06-17-03, 10:45 PM   #6  
knuckles
A bad DPFE sensor is the most likely cause of a P0401, P0402, or P1401 or P1402 on any Ford.

These are horrible little sensors. Ford has yet to design a decent one. They fail with alarming regularity. They're so BAD that Ford recently issued a TSB telling techs not to bother diagnosing the problem, but rather just replace the DPFE if any of the above codes are stored.

You can easily test the DPFE sensor if you have a scan tool.

Simply pull up the DPFE PID on the scan tool & excercise the EGR valve with a vacuum pump while the engine is running. The DPFE value should change as the EGR valve is opened & closed. If the value remains fixed low or high, the DPFE is bad.

 
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06-17-03, 11:05 PM   #7  
I yield to Knuckles post. My experience was not noteworthy to take action. I was merely upset that the DPFE did not solve my problem.

 
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