Coolant sensors. Please sticky when all is done.

CyFi · 11-18-2006, 07:46 PM

Ok i have drawn up a picture, i have done much searching and im getting really mixed up results from people who cant decide what thing on the coolant neck does what. From my understanding, Coolant temp sender units only have one wire, but i see this nowhere on my 5sfe coolant neck.

Please define the following (i will edit in the correct things when the answers are confirmed):
Blue: Cold start timer.
Green: Thermal VSV for evap. or purge.
Red: Temp. sensor to the ECU.

Yellow: Fan temp. switch.

TomsMR2 · 11-20-2006, 02:47 PM

green is a thermal VSV for evap or purge.. one of the two. its on the engine lid on the emissions diagram

blues cold start timer, red is temp sensor to the ECU. theres a single wire under that assy thats the sensor for the dash gauge. its hard to see, but its under there.

yellow is the fan temp switch.

tHe kNiGHt FaLL · 11-28-2006, 07:32 AM

no sensor has one wire....

coolant temp is a NTC Thermistor
negative temperature coefficent

it has a 5 volt reference wire and the returning signal wire to the ecu...

the radiator also has a temp sensor for the fans...

the o2 sensor is upstream before the cat and downstream after cat... some have one most have both... they have two wires... unless they are Hego's which mean they have heaters then they have 4 total...

CyFi · 11-28-2006, 10:00 AM

the temp sender only has one wire plugged into it.

TomsMR2 · 11-30-2006, 01:20 AM

yup, that guys wrong. oil pressure sender also has one wire. those sensors are grounded by their housings. oh hey o2 sensor also has one wire

theres more, im sure.

canadam · 11-30-2006, 01:22 AM

Why don't you just look it up in the BGB ? There won't be any disambiguation there.

CyFi · 11-30-2006, 10:26 AM

they dont show pics of where the stuff is in the bgb

11-18-2006, 07:46 PM	#1 (permalink)
CyFi ShamWOW! Join Date: Oct 2005 Posts: 1,390 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (10/100% )	Coolant sensors. Please sticky when all is done. Ok i have drawn up a picture, i have done much searching and im getting really mixed up results from people who cant decide what thing on the coolant neck does what. From my understanding, Coolant temp sender units only have one wire, but i see this nowhere on my 5sfe coolant neck. Please define the following (i will edit in the correct things when the answers are confirmed): Blue: Cold start timer. Green: Thermal VSV for evap. or purge. Red: Temp. sensor to the ECU. Yellow: Fan temp. switch. Last edited by CyFi; 11-22-2006 at 04:44 AM.

11-30-2006, 01:22 AM	#6 (permalink)
canadam MidshipExpress Join Date: Feb 2005 Location: Beautiful British Columbia Posts: 9,320 Thanks: 111 Thanked 121 Times in 107 Posts My Google Map iTrader Rating: (28/100% )	Why don't you just look it up in the BGB ? There won't be any disambiguation there. __________________

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11-20-2006, 02:47 PM	#2 (permalink)
TomsMR2 Formerly Tom Brokaw Join Date: Feb 2005 Location: Bay Area Posts: 2,138 Thanks: 8 Thanked 165 Times in 138 Posts Blog Entries: 1 iTrader Rating: (0/0% )	green is a thermal VSV for evap or purge.. one of the two. its on the engine lid on the emissions diagram blues cold start timer, red is temp sensor to the ECU. theres a single wire under that assy thats the sensor for the dash gauge. its hard to see, but its under there. yellow is the fan temp switch.

11-28-2006, 07:32 AM	#3 (permalink)
tHe kNiGHt FaLL I Work For Audi Join Date: Sep 2006 Posts: 41 Thanks: 0 Thanked 2 Times in 2 Posts iTrader Rating: (0/0% )	no sensor has one wire.... coolant temp is a NTC Thermistor negative temperature coefficent it has a 5 volt reference wire and the returning signal wire to the ecu... the radiator also has a temp sensor for the fans... the o2 sensor is upstream before the cat and downstream after cat... some have one most have both... they have two wires... unless they are Hego's which mean they have heaters then they have 4 total...

11-28-2006, 10:00 AM	#4 (permalink)
CyFi ShamWOW! Join Date: Oct 2005 Posts: 1,390 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (10/100% )	the temp sender only has one wire plugged into it.

11-30-2006, 01:20 AM	#5 (permalink)
TomsMR2 Formerly Tom Brokaw Join Date: Feb 2005 Location: Bay Area Posts: 2,138 Thanks: 8 Thanked 165 Times in 138 Posts Blog Entries: 1 iTrader Rating: (0/0% )	yup, that guys wrong. oil pressure sender also has one wire. those sensors are grounded by their housings. oh hey o2 sensor also has one wire theres more, im sure.

11-30-2006, 10:26 AM	#7 (permalink)
CyFi ShamWOW! Join Date: Oct 2005 Posts: 1,390 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (10/100% )	they dont show pics of where the stuff is in the bgb