Last halloween the CEL turned on and I didnt get it checked for a long time. Eventually I took it to autozone and they read the P0401 code, insufficient egr flow. About three, four weeks ago, the engine would occasionally make weird noise, like some weird vibration, to me it sounded like the gear wine of remote control cars. About a week after that, the CEL went away, and its been off ever since. Did i burn out the cel on the dash, or did the problem really go away?

sounds like a problem with the FCV(flow control valve).

Would it make the sounds AFTER you turned the engine off? And oscillate on and off a couple of times after the engine was turned off?

When the gears first start stripping it can throw a CEL and make noise, after awhile they will just strip off and no longer make noise or through a CEL. Problem solved.

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I can't believe I am asking this after seeing the words "flow control valve" for so long....What is a flow control valve? How would I know if I have to repair or replace it?

Thanks!

The valve at the entrance of the engine air inlet is sometimes referred to as the flow control valve as based on our understanding in the forum, it is just an intake throttle. The throttle creates a variable pressure drop in certain operating conditions to ensure the correct EGR flow rates. Notice the EGR inlet just after the throttle, right in the low pressure zone. It is also used to reduce engine shutdown vibration by closing off the intake airflow...smoother shutdowns increase the engine mount lifespan.

A broken throttle may increase engine response and have intermittant P0401 codes depending on ambient temperature. However, the increase in shutdown shaking and engine mount deflection should not be discounted. Those with functioning throttles can test the difference in vibration at shutdown by unplugging the throttle wiring for a couple cycles and then plugging back in for a couple more. You can feel the difference in the seat and visually by watching the engine. The effects may vary as the mounts age.

We stress the engine mounts enough with the off-roading and keep the throttle working at shut down to minimize the self inflicted abuse.

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I figured it was the FCV. I'll take a look at it one of these weekends. There is no noise after i turn the engine off, the noises stopped around the same time the CEL went away.

just at thought... i have a boost/vacuum gauge... and i know this is normal operation.... when i shut down i see it pulls a vacuum... i wonder if the FCV was removed or not working properly if it would do this

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Trevor

'05 Limited CRD Inferno Red Pearl Coat
Home made provent installed @ 35443, SEGR installed @ 35466, Fumoto valve @ 37500, trans and transfer case skid, In tank pump installed @ 43500, Suncoast TC & Transgo Shift Kit @ 44730, EGT, Boost, Trans temp gauges, Samco hoses, Rebuilt Trans w/ HD454RFE kit @ 56K, Inmotion Stage 2 @ 56K