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Discussion Starter · #1 ·
The "Emissions Problem" dash light came on while I was on the road between LA and SF.
The Owner's Manual indicated that the car might go into "limp home mode" which did not sound good with another 600 miles before home. I stopped by Livermore Jaguar to get it looked at and they got me in and out in an hour with great service.
It was a "stuck" DEF level sensor. The readout indicated that it has registered as stuck twice on engine startup, claiming 1800 miles to empty. That is not implausible (2400 miles on the car). They cleared the codes and it has not recurred in the last three days (I'm still out of town).
But...
They indicated that if the sensor gets stuck at zero, the car will not start. And can not be made to start. And the lead time for the part is two weeks. And they had already had a customer with that problem.
Not great if you are on a road trip!
Does anyone know if this is a mechanical float system which might be amenable to getting whacked with a hammer or otherwise shaken if it sticks?
 

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That make me nervous.. Mechanical floats are old technology, if true.. Even my JGC has a RF sensor that indicates the DEF level... Its not exact but is accurate enough in quarter tank increments to know where you are.
I just dump 2.5 gal every 5K miles and nary a problem....
 

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Discussion Starter · #3 ·
That make me nervous.. Mechanical floats are old technology, if true... I just dump 2.5 gal every 5K miles and nary a problem....
I have no idea if it is a mechanical sensor. But if those "stick" there is hope!
This was just a heads-up that a DEF sensor hiccup can disable the car, without warning and without immediate remedy. Pretty sure that the mechanic who related the story usually works on the Land Rover side, and the failed sensor might have been on one of those. But that bit is probably identical for the Jag.
 
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Beginning to think this could be the issue with mine.... Dealer says now ( 2ND trip back...) that the computer and the sensor are sending each other mixed signal and right today, he can't tell if it is the DEF sensor or the PCM that is causing the thrown code for the CEL.. he SAYS he is waiting for a special scanning tool to use next Tues to determine if it is a DEF sensor or PCM error. Hope this isn't the beginning of a long term runaround... You know when they have it 3 days and don't call, they prob don't know what to say....:(
 

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See my post in the DEF System Failure thread. They told my wife it was a stuck float (sensor?). I thought they replaced it, but perhaps they just made sure it wasn't sticking. I'll check the service records and report back. It may be a few days. My wife is out of town with the F-Pace.
 

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I thought I'd post this article on DEF.
What Happens When the Diesel Exhaust Fluid Runs Dry? We Put It to the Test | News | Car and Driver | Car and Driver Blog
I did'nt know DEF will freeze! I wonder how that will play out after leaving your FP overnite while visiting the ski slopes?
I'm going to try to research the mechanism and system for measuring the DEF in our tanks.
Is it a float? is it measured by weight or by electrical conductance? or the sinister LASER?
I'm sure someone will come up with a temporary bypass to fool the sysem into thinking the tank is full so no one gets stuck "high and dry"..
Lets get this done! ; )
 

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That make me nervous.. Mechanical floats are old technologwhich



y, if true.. Even my JGC has a RF sensor that indicates the DEF level... Its not exact but is accurate enough in quarter tank increments to know where you are.
I just dump 2.5 gal every 5K miles and nary a problem....

Which DEF brand do you purchase?
 

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I use Wal mart brand for appx 7.88 for 2.5 gal. As soon as you get a notification on dash of impending DEF level low, just dump in 2.5 gal and go on about your business for another 3-5K miles. There is no need to buy PEAK or any other Higher priced DEF, more expensive is not better. Wal mart brand has the same OEM ISO approval as any of the bigger names. I'd bet anything they are bottled in the very same plants on the same lines with the same fluid... Never had a problem....
So far 1 month down and no CEL return ! :):) Running great !
 
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it doesnt matter if you have 5 gallons of def in it if the sensor is bad & tells the computer that it is empty it WILL go in to limp mode you better start walking cause their is nothing you can do on the side of the road to fix it
 
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