1997 Ford Taurus Rough cold idle with a P0402 code

JUSTDON

MEMBER
1997 FORD TAURUS
6 CYL
FWD
AUTOMATIC
117,000 MILES

When the car is first started after sitting overnight, the idle is rough with a "chug" to the engine. If I do not wait until the idle recovers, goes to high idle, and settles in at about 1000 rpms before driving, a code P0402 (EGR Excessive Flow Detected) is set. The code will remain through a certain amount of startups and then clear itself.

Can anyone advise me where to start on finding the cause?

5 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Excessive carbon deposit in EGR, holding the valve partially open. Remove and clean/replace EGR. Or defective EGR position sensor, but since it is Chugging, more likely to be EGR.

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Tuesday, July 14th, 2009 AT 9:08 AM

JUSTDON

MEMBER
150 POSTS

Thank you Merlin.

Would the EGR position sensor be the TPS?

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Saturday, July 18th, 2009 AT 6:20 AM

MERLIN2021

MECHANIC
17,250 POSTS

No Don, it's right on top of the engine, it has the two rubber hoses from the exhaust pipe that connects to the EGR, and an electrical connector. Be careful with these hoses, they tear easily.

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Sunday, July 19th, 2009 AT 6:08 AM

JUSTDON

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150 POSTS

Merlin,

Sorry for the delay on responding. You hit it on the head again. Removed EGR and cleaned it and the ports. Idle is fine with no codes. Thanks a bunch!

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Sunday, August 2nd, 2009 AT 2:32 PM

MERLIN2021