How to fix a jaguar x temp gauge fault - 1992 Jaguar XJ6

the first thing to check is to feel if the radiator is hot, if the radiator feels hot and the engine is also hot the coolant is circulating ok then the problem is more than likely electrical, the temp gauge gets its signal from the engine control module the coolant temp sensor sends coolant temp signal to engine control module for engine managment purposes then passes it to instument pack/gauge, if the sensor was at fault you would have engine running problems also,with poss fault codes logged, if the engine and rad are cold/only warm after the engine has been run for 15 mins or so it sounds like the thermostat is stuck open but you have changed that. i have had faulty new ones in the past and have had to test them in a pan of boiling water, hope this is some help to you.

this warning can be flagged by lots of reasons you really need to get the fault codes out of the engine control module but the common causes i have found after working on these cars for a few years are air leaks after the mass air flow sensor, sticking throttle butterfly in the throttle body, the throttle itself, lamda sensors, and knock sensors, and because the temp gauge does not give you a true temp reading the engine could be overheating the clue to that is the rad fan always running

You can't.. Best to get the temp gauge working before you drive it as an engine will overheat within 10 minutes if you have a fault

check coolant level

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You would need to study the wiring diagram to answer your final question.

The temp sensor of a basic pre-computerised temp gauge mostly just has a single wire and when a gauge doesn't work it can be tested by grounding that wire which then should result in a full scale reading from the gauge. If it doesn't the supply, gauge or wiring is at fault.
If there is a full scale indication the sensor could be faulty or perhaps the engine is too cool.

When electronic engine management came along the temp gauge was increasingly driven by the computer from the main sensor and the single wire type was deleted.

Hi,

I had this problem about a year ago on my 2004 S Type diesel. It's not uncommon and the end result was that it's a wiring fault in the front wiring harness. This is a major hassle to fix and involves taking the fron bumper off. The Jag main dealer did this but the problem came back. I checked other forums and it seems there was a batch of rogue wiring harneeses which Jag bought cheap from Romania in 2004 and fitted to S types. These had moisture in them when manufactured so eventually most of the wires corrode over time - but from the inside! Jag know about this but will not fix under warranty. I ended up spending £1200 to have a whole new front wiring harness fitted - problems gone away now.

1. check electric fan comes on.( this is done by bridging the wires coming from the switch on the rad
2. replace themostat could be intermitant sticking, i am not sure but there may be 2 one in the engine and one in the water pump, depends on the engine set up

What does your engine temperature gauge indicate? Is it on the low side even after the engine runs for a while? If the temp is always on the low side of the gauge, you probably have a thermostat that is stuck in the open position (or possibly someone removed it and did not replace it). If the above describes your engine temperature, and you change the thermostat, it should 'fix' the fault code and shut it off for good.

the gas gauge is not related, that would be a defective gas gauge sending unit in the gas tank, the check engine light indicates that one of around 200 poss faults has occured in the electronic engine controls, you will need to have the OBD 2 engine control system tested for the fualt code that is stored when the light is turned on.

Does anyone know where I find the sender unit? I have the exact same proble.