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Ford Taurus SE 2000 code P0402
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oddgca
User
Aug 25, 2012, 10:00 AM
Post #1 of 4
(6523 views)
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Ford Taurus SE 2000 code P0402
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Hi,
2000, Ford, Taurus SE, 3.0, 142270 km.
The MIL light came up yesterday. Using a Digital OBD2 Car Reader a DTC code P0402 (Exhaust Gas Recirculation Flow Excessive Detected) is on. What can be the problem? Is it a serious problem for the engine? What can I do to rectify it? I am quite a handy part time mechanic and a retired electrical engineer.
Any of your help would be greatly appreciated.
Otto
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Discretesignals
Ultimate Carjunky
/ Moderator
Aug 25, 2012, 2:43 PM
Post #2 of 4
(6485 views)
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Re: Ford Taurus SE 2000 code P0402
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How does the engine run? If it is running rough, check for an stuck open EGR valve. If it is idling fine, you probably have a faulty EGR backpressure transducer aka DPFE (differential pressure feedback exhaust) sensor.
If you want to test the transducer, you can do it with a volt meter back probed into the signal circuit of sensor's the connector. The DPFE is basically a pressure differential sensor (MAP) sensor that compares pressures across an orifice as EGR gasses are flowing into the intake. The sensor outputs 1.0-4.5 volts depending on how much the pressure difference is. With the EGR valve closed you should see around 1 volt and with it open while increasing the engine speed should be around 4 volts.
They usually fail from corrosion from acids and moisture in the exhaust system.
Don't get the hoses switched. If the hoses look bad, you'll have to use special hoses designed for high temperature.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Aug 25, 2012, 2:48 PM)
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oddgca
User
Aug 27, 2012, 4:00 PM
Post #3 of 4
(6451 views)
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Re: Ford Taurus SE 2000 code P0402
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The engine runs relatively smooth. I banged against the EGR valve a couple of times to get it loose. Nothing changed. The MIL light stays on.
Next I measured the voltages at the wires connected to the DPFE:
The upper wire (BLK/GRN) reads 1.35 V constant at idle and higher revolution. It seems to be the sensing wire.
The second wire from the top (GRY/RED) seems to be the negative and measures O V against the negative terminal of the battery.
The third wire (BLK/WHT) reads 5 V constant and seems to be the reference voltage.
Further I tried to test the DPFE sensor (Type F7UE 9J460), by applying some suction to one of the ports and monitoring any changes on the sensing output. However the two hoses sitting very tied on their port studs and I could not get them disconnected. Is there a way to loosen them up without damage? Maybe by applying some W40, oil or other stuff?
Please let me know, how I should proceed to get the problem fixed.
Regards, Otto
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oddgca
User
Aug 28, 2012, 7:04 PM
Post #4 of 4
(6429 views)
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Re: Ford Taurus SE 2000 code P0402
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I like to inform you, that the problem is solved. I purchased a DPFE of the same model taken off from a scrap engine. The seller assured me, that the engine was running well and the sensor is in order. The sensor came also with its small connection hoses, since I had to cut off the ones at my car.
I had my doubt that the replacement sensor works well, because its output voltage was about 1.3 V without any hoses connected and not 0 V as I suspected, since there was no differential pressure. Maybe the diaphragm surfaces are different in size of each port.
Let’s hope, that the sensor will hold for some years.
I thank you very much for your help!
Regards,
Otto
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