My 2006 Range Rover sport kicked into an F fault and then went to limited gears and special systems shut down. I also had a check engine light for an oil temp sensor fault. Turns out that the temp sensor causes the fan to run harder that causes the transmission sensor to think that the engine has a vibration which kicks in the tranny fault. These trucks are too smart for our own good! New sensor and plug ordered. Hopefully that will do the trick. Stay tuned. Phil





2005 LR3
2006 Range Rover Sport

 

Keep us informed as to your success. Yes, you are correct, these units are just too smart for the owners good anyway.

When I read your symptoms, I first thought it might be a defective radio noise filter, however that is usually a complete showstopper. 10 amp F30E fuse blows and the tranny computer is depowered leading to no vehicle movement. The engine will run but the vehicle goes nowhere.

Below is a link to a related file.

DISCO3.CO.UK Photo Gallery - ZF 6HP26 Automatic Transmission in LR3/Radio Noise Filter Transmission Electronic Control Unit

 

Believe it or not it was the oil temp sensor! Changed it and all seems well. Tranny and engine are working and running great. Thanks. Phil

 

That is tricky - you have good guys who understand your machine.

The oil temp sensor is located sort of under the engine - beside the oil filter I think. It is somehow tied thru the computers to the water temperature sensor located on top near the thermostat and then to the temperature gauge on the dash. As such the temp gauge can be reading oil temperature rather than coolant, but the bias is first to the coolant.

Naturally to do this, all this goes thru the engine computer that gossips to the tranny computer that chats with the cooling system controls and it goes on.

I use the word gossip as not always are the computers telling the truth - that is where the mechanic shows his worth - sorting out the real from the story telling.

Well done and thanks for the update.

 

"Gossips" is hilariously accurate in describing the system communication

 

So we are clear, the temp gauge on the RRS always showed normal, based on the coolant temperature. It never showed hot on any gauge or light on the dash. The only dash warning was the check engine light and the code that I read showing that it was the oil temp sensor (hot). Thanks again. Phil

 

Yes, I would say that did require clarification.

It is rare that the error codes generated accurately tell what part is defective. That was a real miracle - you definitely live right.

I think that if the temperature gauge needle does move, something really bad has happened.

About the only time I have heard of it reading anything other than OK was when the main harness plug into the instrument panel printed circuit board gets loose/disconnected and cuts off signals to the needle.

In normal operation, apparently the needle is computer dampened to pretty much smooth out any variations in coolant or oil temperature to the point that the needle always sits in the middle except when the engine is off.

 

Correct me if I am wrong but the temp sensor on the dash is for coolant, not oil temp.

 

Page 81 and 82 of my Owners Manual call the gauge in question, (4), the one with the needle showing the thermometer symbol behind it, as a Temperature Gauge. As you might realize, that is perhaps less clear than it might be and tends to raise more questions than it answers.

As follows, page 73 and 84 however uses the words "engine coolant" so that should be the last word - right? O, if it were only so simple!

2. Temperature Gauge

At normal operating temperature, the pointer
will be positioned midway between the RED and
BLUE segments of the gauge (the precise
position will vary according to climatic
conditions).

If the pointer moves above the mid point, the
engine coolant is becoming too hot. Should the
pointer move INTO the RED segment and the
RED warning indicator within the gauge
illuminates, severe engine damage could occur
(under these circumstances, the air
conditioning may switch off and engine
performance may reduce in order to minimise
engine load).

Stop the vehicle as soon as safety permits and
switch off the engine and allow to cool down. If
the problem persists, seek qualified assistance
before continuing.

The next part however is where it gets less clear but more interesting. Note the highlighted line near the bottom of the section excerpted from the LR workshop manual, section 303-14B Electronic Engine Controls - 4.4L.

While it does not exactly say the oil temperature will display on the dash gauge, it does say the engine computer will use oil temperature values in lieu of suspect coolant readings - presumably a defective coolant sensor rather than an actual malfunction within some component of the cooling system.

4.4 Litre Petrol V8

The V8 4.4 Liter engine is controlled by an Engine Control Module (ECM) manufactured by DENSO.

Engine Coolant Temperature Gage

The engine coolant temperature gage displays the engine coolant temperature to the driver.When the ignition is off, the pointer needle returns to the cold position.

The engine coolant temperature sensor is connected to the ECM which monitors the sensor signals and converts the signals into a value for the engine coolant temperature.

This information is transmitted on the high speed CAN for use by the instrument cluster and other systems. For additional information, refer to Electronic Engine Controls (303-14A)

The engine coolant temperature gage is the same on all pack variants. The gage has a blue segment for low temperatures and a red segment for excessively high temperatures.

For normal operating temperatures the gage needle pointer is positioned centrally in the gage display zone. The needle pointer position translates to the following approximate temperatures.

Engine Coolant Temperature ºC (ºF) Needle Pointer Position

Ignition off Park position
40 (104) Cold Blue segment
75 - 115 (167 - 239) Normal
120 (248) Start of hot (Red segment)
125 (257) End of hot

ENGINE COOLANT TEMPERATURE SENSOR (ECT)

The sensor is located at the front of the engine in the water pipe below the throttle body. The ECT sensor is a thermistor used to monitor the engine coolant temperature.

The engine coolant temperature sensor is vital to the correct running of the engine as a richer mixture is required at lower block temperatures for good quality starts and smooth running, leaning off as the temperature rises to maintain emissions and performance.

The sensor has an operating temperature range of -30 Degrees Celsius to 125 Degrees Celsius.

When a defective coolant sensor is detected, the ECM uses the oil temperature sensor value.


ENGINE OIL TEMPERATURE SENSOR

Oil temperature is monitored through a temperature sensor mounted in the oil system. This component is a NTC (negative temperature coefficient).

The sensor is mounted next to the oil pressure sensor at the front of the engine and locates into the oil filter bracket.


FUEL TEMPERATURE SENSOR
I thought I would just throw the Fuel Rail temperature sensor in for fun.
There is also a Mass Air Flow Inlet Temperature sensor as well.

The fuel rail temperature sensor is located in the rear of the RH fuel rail. The sensor is an NTC sensor, which is connected to the ECM by two wires. For additional information, refer to Electronic Engine Controls (303-14B Electronic Engine Controls - 4.4L)


In summary, I would have to concede that when all is working well, the temperature gauge on the dash reads Engine Coolant temperature. When a problem evolves, the needle reading is less certain.