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Coolant Temp Sensor...

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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rspi
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Re: Coolant Temp Sensor...

Post by rspi »

Our's didn't work right after the car overheated just once. The new one worked good for 2 weeks but after I changed the head gasket it only worked for 2 days after that. I was thinking it was messing up because it was burping air but it stayed bad for a week then caused our battery issue.
'95 855 T-5R M, Panther - 22/28 mpg, 546,000 miles
'95 955 T-5R Yellow Wagon, Lemonade, 180,000 miles
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jimmy57
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Post by jimmy57 »

cn90 wrote:Interesting! I still have the original ECT and car runs fine at 120K miles.

Question: is this a problem with the ECT itself or the Connector?
Connector.
Usually occurs due to it being unplugged or any work in that area where the connector could be disturbed.
I suppose road salt spray could give you issues if the plastic disintegrated and fell off with time.

JimBee
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Post by JimBee »

When I went through the 850 connections prior to a trip last summer I struggled to get that one apart. When I finally succeeded it was obviously corroded, so I took my dremel tool with a tiny wire brush to clean it up as well as possible, then a pick with a barb on the end to scratch the insides of the tubes, before putting it back together with some dielectric grease. I've pulled a couple from wrecks and they always seem corroded. If that happens to mine again, I might just cut the pigtail and put in some new connectors that are more protected from the elements.

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erikv11
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Post by erikv11 »

Do some reading, you will find the aftermarket ECTs are notorious for failing. I consider this a dealer-only (or junkyard-only) item.
'95 854 T-5R, Motronic 4.4, 185k
'98 V70, T5 tune-injectors-turbo, LPT engine, 304k, daily driver
'06 S60 R, 197k
'07 XC70, black, 205k
'07 XC70, willow green, 212k
'99 Camry V6 :shock: 153k
gone: '96 NA 850 210k, '98 NA V70 182k, '98 S70 NA 225k, '96 855 NA 169k

cn90
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Post by cn90 »

Hmmmm,

If this is truly a connector problem, why does every thread in this Matthew Volvo forum and Volvospeed forum recommends people change their ECT when they replace the thermostat???

To me, it makes more sense to inspect/clean/lubricate the connector?
2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+

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erikv11
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Post by erikv11 »

You're not reading the posts cn90, don't be fooled by this one thread - the connector can be a problem and should be checked, but more frequently the sensor itself is bad, e.g. wires falling apart, internal connections bad.

If the connector was usually the problem, then replacing the ECT wouldn't usually fix it.
'95 854 T-5R, Motronic 4.4, 185k
'98 V70, T5 tune-injectors-turbo, LPT engine, 304k, daily driver
'06 S60 R, 197k
'07 XC70, black, 205k
'07 XC70, willow green, 212k
'99 Camry V6 :shock: 153k
gone: '96 NA 850 210k, '98 NA V70 182k, '98 S70 NA 225k, '96 855 NA 169k

mrwillie
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Post by mrwillie »

Not to thread jack, but.......

I had issues today after replacing the alt yesterday. I know the CTS was unplugged/moved around alot. Other than an intermittant error code that I have had a few times since I've had the car, this is the first time that its given me any issues. I'll try this and order one tonight.

Thanks for the info

loveMy850
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Post by loveMy850 »

when first thing in the morning car starts fine, then after that its kinda hard starting, Ive changed the fuel pump, filter, got all vav. leaks that I could find, cleaned my maff sensor, whats the proplem anyone!

rguzz
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Post by rguzz »

The connector can be found @ the dealer. Problem is you need to wire it in, and getting your big fat hands in there means removing upper rad hose +- power steering hose. If you wire a new one in, give yourself extra length so you can route as far from the intake as possible (theoretically to a less hot space).

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