Hello. I have a question that has come up after working on my 2004 XJ8 NA. I recently had the valley coolant hose burst, so I dug in and fixed that. While trying to remove all the connectors to free up the harness and make room for the intake repair, I noticed that I was unable to remove the sensor to the passenger side fuel rail. It appears to me that the little clip was broken already, and, being really far in the back, I could not get it off. I commenced to lift the intake manifold without fully removing it, replaced the hose and went on with the job. The good news is that it all went back together, and I fixed the coolant leak. However, now I am getting a P0182 code, which is apparently low voltage from that fuel temperature sensor, and that throws a CEL every two or three times I drive the car.

I have gone back and tried to fiddle with it, but I still can't get it off to inspect, clean, remove, etc. Can you guys confirm a couple of things?

1) Is the fuel temperature sensor the one in the back at the end of the fuel rail? 99% sure it is from the pictures I've seen, but thought I should check.
2) Mine will screw in and out several turns, which strikes me as odd. Is it supposed to be screwed in all the way tight? Since I cannot disconnect the connector, as I screw it, it is stressing the wire, so I am reluctant to keep trying.
3) Does someone have a picture of how the outside part of the connector should look so I can see if mine is broken? How is the clip supposed to work?
4) How would one realistically repair a broken connector back there? With unlimited patience, a broken connector could be cut off spliced in to a good one, but where would one find such a connector? The wires seem pretty small.
5) Is there a better way, like to "spoof" the signal, so the car thinks it's OK and the light goes away?

This car has 165,000 on it and is by no means perfect, so I can't justify letting a professional spend all day on it, possibly making it worse. The harness is old and brittle. I am grateful for any suggestions.

 

UPDATE: I made it worse. In my constant attempt at disconnecting the connector, it is now fully broken off with the wire dangling. There are a few inches of wiring that I maybe can use. How would one find the connector pigtail for this?

 

Make a mechanical joint by twisting the wires together
and cover joint in solder.

Slide shrink wrap over the bare area and heat to shrink.

 

That is indeed the fuel temp sensor, and while you can touch it with the manifold installed on the engine, you can't get a good enough hold on it to remove it. And you can't even touch the MAP sensor on the back of the manifold until you do as you did, lift the manifold, and then pull it forward to the extent those wires will reach. Once the manifold was moved, I didn't find it that hard to disconnect, but I didn't even try with it in place.

Hindsight, I know... Maybe helps the next guy who comes across the thread needing to do this.

 

Thanks for the input. It seems like it's running OK without a working fuel temperature sensor, so I'm not going to worry about it until it gets cooler and I feel more motivated.

The thing that I am a little confused about is that I see what appears to be a only a single yellow wire coming out of the harness. Hopefully there's some other wire that I'm not seeing in there somewhere.

If I can't connect and get this working again, does the fuel temperature sensor really matter to engine performance? Is it more of a winter issue?

My other course is to replace the entire engine harness. I see some eBay for $200 ish. Besides the hard to reach MAP sensor, is there any reason why it couldn't be done from the top without lifting the engine?

 

Just wanted to close out this thread with the final resolution.

I was able to access the remaining bit of harness wire that was previously connected to the fuel temperature sensor. Inside the black plastic protective harness, there were two wires: yellow/orange and black/green. I used some scissors to reach back and score the insulation for about a half inch and then removed the insulation with my fingernails. Once the insulation was removed, I used some "lever nut" connectors to splice in a length of about 8 inches of new 18 AWG wire. The lever nuts took only a few minutes vs. trying to solder way back there. This made it easy to work with the wire, since it was long enough to handle without having to reach to the back of the engine. On Amazon, I found a pigtail or connector. It turns out that the Jaguar fuel temperature sensor has the same size and shape connector as the Toyota coolant temperature sensor connector. I purchased a new Dansk fuel temperature sensor from Parts Geek for $18 (69715NC). It can also be found using the Land Rover part number LRA1600BA.

I purchased my pigtail/connector for the sensor via Amazon for $9 using the part number 158-0421 for Toyota. I later cross referenced on Rock Auto and it is there also for about $10.

Once I had the temperature sensor and the pigtail connector, I connected them and then used two more lever nuts to connect to the wire coming up from the harness. I used electrical tape and duct tape to wrap the wire and lever nuts so there wouldn't be any movement. This fixed the problem with the CEL and the car runs perfectly. In my case, I was not able to remove the connector from the sensor on the rail. They are seized or glued together or something, and I didn't feel like I wanted to open the fuel rail and potentially cause another problem. So I just tucked the wiring and the sensor out of the way. My belief is that when the engine is cold, the sensor will be about the ambient temperature, and it will be read by the ECU as cold and adjust the fuel mixture to be richer. As the engine bay heats up, the ECU will adjust to the higher temperature and adjust the mixture more lean until it gets the optimal mix. I checked the fuel trims and it is working normally, so I am calling it good. It is probably somewhat less accurate than it would be, but I doubt it will make any real difference. The car has been driven 500 miles since the fix without any problems.

Thanks to everyone for their input. I'm glad the issue with the valley coolant hose was able to be resolved without taking it in, as that would have been expensive. I was also able to fix other things while it was opened up like my EGR hoses. All in all, it's a happy ending.

 

Thanks for this!

For those greybeards among us still holding out for proper "Western Union splices" or MIL-SPEC Burndy connectors, the handy "lever nut":

https://www.wago.com/us/discover-wir...ing-connectors

'Ideal' and others among the "usual suspects" also carry them.