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Old 10-27-2006, 19:48   #1 (permalink)
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how do I fix 2001 grand marquis showing obd code 401?

My 2001 grand marquis gives obd2 result code 401 (egr insufficient flow). What is the most likely cause and how can I fix? Where is egr valve situated?

Thanks!!
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Old 10-27-2006, 22:09   #2 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

Insufficient EGR flow? Sounds like a stuck/sticking EGR valve. In the old days the EGR valve was attached to a spacer that was sandwiched between the carburetor and the intake manifold. At the back of the spacer was a vacuum-controlled diaphragm - it wasn't tiny, and easy to spot. This controlled a valve.

But now we're talking about much newer technology. I haven't seen a 2001, but you can bet the EGR valve will be found somewhere on the intake manifold, since the purpose of the EGR valve (Exhaust Gas Recirculation) is to re-route some of the exhaust emissions back into the intake to be re-burned. It could still potentially be vacuum-controlled, but I would suspect it could also be electronic, too. Consult with a shop manual, or a knowledgeable person who owns a 2001...

Regardless of the technology, if something is telling the computer there is insufficient EGR flow, you will very likely be faced with replacing the EGR valve. It's also possible to have a blocked passageway in the EGR system, but to have a faulty EGR valve isn't uncommon (and this isn't restricted to Crown Vics).

You'll be happy to know that replacement of this valve is not a difficult procedure.
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Old 10-28-2006, 08:28   #3 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

Ford has a recall about this very problem and have issued a revised DPFE sesnsor which is what controls the EGR valve. they also extended warranty coverage on this part to 4 yrs/50K

go check with your local Ford dealer and see what they say.
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Old 10-29-2006, 16:20   #4 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

I find many times it is the egr ports plugged up. Its not a bad fix. Try to apply vac to your egr valve, if rpm does not change and you hear the valve slap back whe you remove the vac. then it si most likly pluged ports. You will need to pull off the lower throttle body. 4 bolts be carefull not to drop them. One of the small pocket magnets helps. Also a pair of long nose pliers to pull off some lines helps. You should get a new gasket. but I have reused them before. some tune up cleaner and a pick or small screw driver to remove the shit from the ports and you are good to go. Good luck. Don't let a shop charge you more then 2.5 hrs to do this including diag if you decide to bring it in some where.
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Old 10-29-2006, 17:02   #5 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

Intake manifold on this motor is composite plastic, so it's very unlikely the EGR ports are clogged.

Ford has a know problem with the DPFE sensor on this model and has a revised part # check with your dealer to see if your car falls under the extended recall, the repair maybe free.
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Old 10-30-2006, 16:28   #6 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

Hope you fit in under the extended coverage for the sensor. Like was said by 88grandmarg they did have huge issues with sensors not lasting. So it is a good chance that is your concern. If you do end dealing with up plugged ports here is a picture. The part you have to remove to get to the ports is # 17 in the picture.

http://img230.imageshack.us/img230/4033/46lyi1.gif
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Old 11-11-2006, 13:16   #7 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

Thanks for all your useful suggestions and support. I have now replaced the EGR valve, DPFE sensor (pressure sensor) and EVR (modulator valve). The check engine light went out for approx 5 to 6 days and car ran OK.

Today car stumbled and hesitated, similar to before. Check engine light went on again with OBD2 code 402 this time. Again I can smell unburned fuel (bad egg smell). I have checked all vacuum leads and changed spark plugs.
Any suggestions would be appreciated.

Thanks!
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Old 11-11-2006, 19:52   #8 (permalink)
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Re: how do I fix 2001 grand marquis showing obd code 401?

"bad egg smell" is typical of a bad catalytic convertor; not un-burned fuel. The cat(s) may be bad.
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