Hi all,
My check engine light is on due a to an "FF14", or coolant thermistor problem.
anyone else ever had this? Im at work atm, but will check my coolant levels etc when i leave but any ideas before that greatly appreciated!

 

The coolant thermistor measures coolant temperature, and this is fed to the ECU. It is one of the major inputs to the fuelling algorithm, the other being mass air flow.

 

Hmm so this isnt looking good. See there are no reported problems on my dashboard, but obviously something isnt happy. Could it be possible that the engine may be overheating but not sending the info to my dashboard? Generally the running is fine, but yesterday I drove it back from work and it was taking sharp intakes, almost like a misfire, when i backed off the throttle. Not everytime, but on the odd occasion. And then I got stuck in another queue and the check engine light came on, I put the car into neutral as we had come to a standstill and then he cut out! He started up ok but i wonder if this is something to do with it?

 

Apparently it's your coolant temp sensor for the fuel injection system...or something related to it... that isn't happy, thus the "FF" diagnostic code. As mentioned, this is an important sensor for fuel metering.

I suggest isolating and repairing the "FF" fault and see how she runs.

Cheers
DD

 

So, the "FF" means fault? I couldnt find any info on the letters, just the numbers part.

So would I need to change the thermostat? What about the thermistor? Where is that? And should I go for a coolant change as well? So many things!!

 

FF = Fuel Fail. 14 = Coolant Temp sensing.

Had a similar problem with my 4.0 XJ40, turned out to be the wire on the T/Stat. Temporarily fixed it with insulation tape 6 years ago!!

Took me a while to get my head around the message FF being directly related to a broken water temp sender wire in my case.

The problem I saw was that the connector is vertical and is just about the most exposed high point on the engine, thus easily bashed and damaged.

Might be worth a look at the connector.

 

Not so fast ! :-)

The car's on-board computer has a certain degree of self-diagnostic ability and it is telling you, by code number, that it sees a fault with the coolant temp sensor.

You *probably* need a new sensor but it might be a chaffed sensor wire, dirty contacts at the sensor connector, or some other fault that the system is interpretating as a sensor problem.

You might be overheating, you might need thermsotats, you might need a system flush....but right now what you need is to isolate the problem that the system is actually telling you about with the FF14 code. Inspect the connector inspect/clean/tighten the connector, visually inspect as much for the sensor wiring as you can see, and, if everything looks OK, go ahead and replace the sensor.


Cheers
DD

 

Oh I see!! FF = Fuel Fault! Fantastic!!
I just assumed it was "Fault Found" lol!!

Right I will get a good look at it tomorrow I think if I Can find the time! I do find it odd how it has just come about all of a sudden! Silly Jack!!

 

By the way, thanks all!

 

For information:
A thermistor is a conductive device that changes its resistance markedly with temperature. A NEGATIVE temp. coefficient temperature thermistor lowers its resistance as temperature rises, a POSITIVE temp. coefficient thermistor raises its resistance as temperature rises. They are most commonly found in tv sets using cathode ray tubes as the display device, where they are used in the degaussing circuit for the screen. These have two mounted back to back of opposite type, and often go faulty, leaving mis-colored patches in the picture. Incidentally, an ordinary filament lamp has strong +ve. temperature characteristics.
Leedsman.

 

Thank you very much for your reply. As suspected I was very busy today so hopefully will have time to look at it tomo!! Cheers

 

By the way, where the hell are they found??
I have looked everywhere on the web and in my manual and nothing mentioned thermistors except on V12 models!!??

 

Look for "coolant temperture sensor"

They are a common item. Any local auto parts store should be able to get one for you...or perhaps even have one on the shelf. Make sure you get one for the fuel injection system as opposed to one for the dashboard temp gauge

It'll look like this: http://www.motorcarsltd.com/jaguar-x...rature-sensor/

Cheers
DD

 

Thanks for that.
I found it and cleaned it then left the engine running for about 20 minutes. It barely got to halfway to N so I put my foot on the pedal and raised the rpm a little, this raised the temp to just below N. Is this OK? Im used to seeing it exactly on the N!
The engine light didnt come on ...

 

Ugh nooooo! I drove to work and back, thats 80 miles, and Jack behaved so well, I was so proud of him! No check engine light, no misfiring!

Then just now, literally just now, the heavens opened outside, so I dashed out in the hopes that I would get the chance to work out where the water was getting into the car on the drivers side ... anyway, thats another story...

There didnt appear to be any water coming in, and then I noticed the time on the clock was wrong so I thought I would change it ...

... and I dont know how to change it, so I thought the ignition had to be on ...

... so I turned the ignition on and then the display read "CHECK ENGINE FF14"

Argghhhhhh!!!!!!! Wheres that come from?!?!?!?! The light on the dash isnt on and hasnt been on at all today?!?!?!

 

Welcome to the world of "electrical intermittents".

Just because the light went away for a day doesn't mean the probem fixed itself. it's there....lurking....waiting !

Cheers
DD

 

No! The light went away therefore it DOES mean that the problem has gone ...

Ugh, well I am not naive to the fact that these old beasties have electrical problems, I just like to think that they dont suffer from them lol! I cleaned the sensor Weds and then he behaved, and then the rain came and it reappeared, and then guess what?? I drove to work this morning and nothing! No light, no code on the trip computer!? Gremlins again!!

 

Re. digital electronic faults: You guys here are now encountering the kind of problems we had to deal with all the time in the electronics industry, mine being security electronics. Unlike analog electronics, where you often can provoke faults with the "mechanical disturbance test" (bashing it), or logical fault-tracing with a voltmeter or oscilloscope, where you know instantly if a things working properly or not, digital electronics has a 'time-delay' effect where, for instance, a circuit initializes itself in a few seconds, and puts a fault on even before you've begun to investigate. There is the extra fault possibility of software errors, not just hardware, possibility of all sorts of random errors. One such was the fact that a controller on a video jukebox mysteriously kept "crashing" during a play, making the publican have to ret. the money -- very bad! It turned out that a particular make of 14pin DIL logic gate chip was not quite fast enough for the job, and "critical-race" conditions applied. Using a Motorola chip instead was fix because it was a few microseconds faster, even though the spec. was met by both. The chip cost 14pence I remember!
Your tools for sorting problems now becomes:--
Visual inspection. With a powerful lens and a bright lamp looking for bad/dry joints and subtle solder splashes.
A small hair drier and a can of freezer spray with a pipe on it. Very often a faulty chip will work ok when heated, but will fault when carefully sprayed with freezer. This also works with electrolytic capacitors. Remembering the time delay effect!
VERY accurate adjustment of +5volt, +12volt and -12volt rails with a quality digital voltmeter. TTL technology is fast and uses +5volt, c-mos is slower but less power greedy and used +12volt and -12volt. The +5volt line is PARTIC. sensitive. Sometimes a slow chip can be speeded up by setting +5volt a tad high at say, +5.2volt.
Checking for "hash" on the power rails with a 'scope. This originates from switch-mode power supplies where the filter electrolytics have had it, usually due to heat and age. The timing of data movement can be subtly degraded due to this "hash".
Hope this might help someone with an electronic car-fault.
Leedsman.