My wife came home from work with a check engine light on the crd. Had NAPA scan it (I don't have a scan tool). p0401 and p0299 "unidentified fuel and air metering error". Easy fix? Cheap fix? or is it time for a GDE tune? What should I do? FYI It has never gotten great mpg's in the 2 years I've had it. 18mpg around home and 23mpg on road trips.
Steve

That code description is not right, but those two codes are related to an FCV or EGR valve gone bad. That was the classic pair that people got in the early days of the CRD. If the FCV is stuck open and the EGR valve stuck closed the GDE tune will smooth things right over.

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05CRD: GDE Hot ECU & TCM tunes, Provent, Cat filter, Facet lift pump, TransGo kit, Florida TC, Samcos, stainless brake lines, HDS thermostat, Renegade light bar,
RL super sliders, Bilstein adjustables, Al's Gen 4.5 Arms, 235/85-16 Duratracs, DTT rear, Elocker front, EVIC+TPMS, Turbo timer, McNally pillar gauges, Weeks Stage II kit.

Thanks. Not sure what scan tool napa uses but that is the read out that was given for the codes. What exactly is the fcv? How does the cost of replacing these parts compare to a GDE eco tune? Would these parts failing explain my poor milage? If so, why just now throwing codes?
Thanks

Flow control valve; run a search on this forum for some chat. Apparently doesn't really "do" much. Chat indicates it typically fails open in which case it can be left alone. If it fails closed or partially closed the butterfly can be removed by removing 2 screws while being careful not to drop them into the engine and then left alone.

EGR can be removed and cleaned to free things up altough removal is a pain, again run a search.

GDE tune mostly shuts off EGR hence the codes go away if the EGR is at all functional.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

The fcv looks like a butterfly in a gasoline engine and on our CRD's it restricts air flow into the engine so the engine will draw in exhaust gas when called for. It also closes when the engine is shut down to smooth out what would be a rough shutdown. It's driven by a electric motor and has gears that strip. The gears were originally plastic but were changed at some point to metal. When I had those codes my fcv made a grinding noise on shutdown. A slight "purr" or "whirr" for a few seconds after shutdown is normal. It's mounted on the driver's side of the engine and you can remove the charged air hose and check that the butterfly is open and when you close it that it springs open. You can also try to clean the EGR valve. Dealer service tech's routinly replaced both of these for these codes.

Generic causes for various codes do not apply or are incorrect for our engines that is why NAPA's discriptions are wrong There's a list of codes in the FSM, see Sam's Noob's post.

Yes it could be causing poor mpg's and it threw codes because it just failed

You have two choices, replace two expensive parts and have the same problem later on or get a GDE tune. Not exactly rocket science There are other advantages to getting a GDE tune like better mpg's and better overall running of our engins

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

FYI the 2005 diagnostic codes are in separate manuals that Sir Sam's post does not have. Not a problem though as those codes are the same or close enough (stability control system excepted) as the 2006 codes which are included in the 2006 FSM.

If anyone cares I have pdf versions of the 2005 diagnostic manuals although I almost never look at them.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

I've been wanting a GDE tune for quite a while now. This settles it, GDE tune it is.

My 2005 CRD went through 3 EGRs and an FCV in the first 11,500 miles. Then, back in 2006, the pair was something like $1100 for parts only. Started having those two codes back in July, and a GDE eco-tune took care of it. Wish I'd done it sooner. And yes, the first tank of fuel after applying that tune got me 4 mpg better on the highway than I'd ever seen before (up to 34.75 from just over 30). Do it.

There is still another option that fixes it 100% forever. It is called the SEGR and there are lots of them out there.

SEGR, Tune, whatever, if the EGR is stuck part way open, it will still have to be fixed or blocked off.

I forgot to mention that Napa reset the cel and although performance nor milage has gotten any better, the light hasn't come back on. This tells me that the egr must be working at least some. I still want to get the eco tune though. This is bound to happen again. I'd say sooner than later...

Am a bit surprised by the fact that broken vacuum hose is not mentioned in your case. Not sure if this would cause a bad mph, but as it blocks the turbo from working correctly, my guess is it could worth checking. It is definitely giving a P0299 code.
See my thread on that:
viewtopic.php?f=5&t=61240

Maybe a very minor vacuum hose hole is the reason, no ?

Good luck !

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Silver CRD
ASFIR skid front & central elements, MOPAR gas tank skid - SAMCO Turbo hoses - 4 breathers extension
2006 gaser airbox - Frankenlift with Koni at front.
Airtex lift pump

Considering the GDE tune for my 06 CRD. CEL off an on for about 2 weeks now, codes p0401 and p0299. Only concern with the GDE tune is Ohio's e-check - which is required in my county. Anyone know if the GDE Tune will negatively impact emission test results?

It shouldn't but if they want to put your 2006 on rollers during the test you need to be aware of the problems that can cause with the ESP program.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

It should sail right through with the GDE tune. Mine do.

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05CRD: GDE Hot ECU & TCM tunes, Provent, Cat filter, Facet lift pump, TransGo kit, Florida TC, Samcos, stainless brake lines, HDS thermostat, Renegade light bar,
RL super sliders, Bilstein adjustables, Al's Gen 4.5 Arms, 235/85-16 Duratracs, DTT rear, Elocker front, EVIC+TPMS, Turbo timer, McNally pillar gauges, Weeks Stage II kit.