coolant temperature sensor

[harrylime]

I'm having my throttle body cleaned to try and improve throttle response and mpg, and having read some posts on here, I was thinking about changing the coolant temperature sensor, thinking it was a cheapish part. I have been quoted around £60 for the snsor at the main stealers, which is much higher than I expected. Is it possible to get pattern parts, anfd if so are these satisfactory?

[Tinonline]

Hi

I recently changed spark plugs, air filter and adjusted the slack out of the throttle cable. 

This has transformed the speed, pick up and sharpness of the engine. I have noticed the difference.

only thing I would caution is that throttle bodies have a layer of protective coating and unless sticking or faulty are best left alone. 

My mileage is 78k and there is nothing on the butterfly...or at least not enough to warrant touching.

[steve2006]

If you can wait a short while the Amayama price for this part (89422-30030) is £22.37 plus shipping.

[harrylime]

Thanks Steve. Can anyone tell me which UCF engine code applies to a 1999 mk 4? I have checked my logbook and the numbers do not correlate with a UCF number

[steve2006]

Should be a UCF20 model

[harrylime]

On 22/07/2016 at 10:28 PM, steve2006 said:

If you can wait a short while the Amayama price for this part (89422-30030) is £22.37 plus shipping.

Steve

How sure are you that this part number will fit a 1999 ls 400? I have seen some on eBay uk for around £25 , quoting that part number, but the compatibility chart states that there are 7 other variations?

[ambermarine]

Hugh

The temperature sensor is very important to the correct fuel mix on the engine management system I put a new one on my Mark1 after a period of time when the revs were too high for two long a period.

It is there to monitor the fuel to air mix required for optimum performance as the engine runs up from cold.

The aftermarket cheaper versions may not be as sensitive therefore defeating the object of having it renewed.

I found that after fitting the Toyota sensor bought whilst in the states( it is fitted to most of the toyota range also) the engine ran a lot better from start up to optimum running temperature and was well worth the extra cost.

[steve2006]

Part 89422-30030 (SENSOR, WATER TEMPERATURE (FOR E.F.I.)) was found on the following models:

	Date range	Model	Frames/Options	Found in diagram
	01/1999-06/2005	LEXUS IS200/300	GXE10,JCE10	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	05/2001-06/2010	LEXUS SC430	UZZ40	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	08/1997-12/2004	LEXUS GS300/430	JZS160,UZS161	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	01/2005-11/2011	LEXUS GS30/35/43/460	GRS19*,URS190,UZS190	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	10/1994-07/2000	LEXUS LS400	UCF20	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	08/2000-07/2006	LEXUS LS430	UCF30	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	01/1998-07/2007	TOYOTA LAND CRUISER	UZJ100	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	01/1998-07/2007	TOYOTA LAND CRUISER	HDJ100,UZJ100	84-04: ELECTRONIC FUEL INJECTION SYSTEM
	08/2002-07/2007	LEXUS LX470	UZJ100

[harrylime]

Thanks for responding chaps, I think you make good points, the sensor being such a critical and sensitive part, it may not be a good idea to economise on its replacement. Tempting when you see the same part for less than half price. No idea what intermotor parts are like, I understand they are OEM on some cars, but perhaps not worth chancing it

[cornershop]

Gents,

I've no record of the coolant sensor being changed, should I go ahead and change it regardless?

I read somewhere about a fuse needing to be removed/reseated after changing the sensor but can't now find that thread.

Needed?

[Tinonline]

In my youth when running an MG Midget my local mechanic said "if it ain't broke, don't fix it."

[cornershop]

Yes indeed, but can I check it's not broken. I've read it's an important sensor, what would be the symptoms of failure?

[The-Acre]

51 minutes ago, cornershop said:

Yes indeed, but can I check it's not broken. I've read it's an important sensor, what would be the symptoms of failure?

Difficult starting when hot, uneven running/revs, completely cutting out and many other problems.  It's amazing what one little sensor can affect.  I wouldn't waste my money unless I had a problem, they rarely play up.

[alien1974]

what fuel are you using? bare in mind the manual says 96 RON or higher, i use either 97 super unleaded or 99 tesco momentum 

[ambermarine]

Shirish

Main symptom of a temp sensor malfunction is high revs for prolonged period after the car as been started from cold.

The car starts and runs at about 1100 revs initial start up A/C off it eventually falls back to normal tickover of 650 rpm as the engine warms to normal if the revs stay above that 650 rpm at around the 1000 to 1200 rpm area the sensor as failed.

This will be apparent at starts from stationary as the transmission will clunk when putting the stick  in drive from park.

[harrylime]

I changed mine due to a sudden, unexpected increase in fuel consumption. Much improved after back to what I would expect

[cornershop]

Mine is fine then, will stay away from the 'search' function :)

[Tinonline]

On 14/01/2017 at 1:16 PM, alien1974 said:

what fuel are you using? bare in mind the manual says 96 RON or higher, i use either 97 super unleaded or 99 tesco momentum 

LS400 mk4 manual says 95 or higher but ok for temp use of down to 91.