Coolant sensor - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

• Coolant sensor by Vohaul on 19 Mar, 2013 23:33
• Argh.....93 aaz jetta
  The coolant sensor on my dash won't stop flashing.... Level is fine.... Temp is fine, car has power, no issues except the stupid light.... Replaced the overflow tank... No difference....
  
  Does the plug going into the overflow tank on these go?
  
  Thanks
  
  Paul
• #1 by wolf_walker on 20 Mar, 2013 09:03
• Did they have that coolant water/antifreeze ratio sensor in that model?  Seems like my 85 had that going on way back.  Little sensor with two pins in the coolant tank.
• #2 by Vohaul on 20 Mar, 2013 16:49
• Quote from: wolf_walker on 20 Mar, 2013 09:03

  Did they have that coolant water/antifreeze ratio sensor in that model?  Seems like my 85 had that going on way back.  Little sensor with two pins in the coolant tank.
  

  
  ya, i think thats the one....sensor is part of the overflow tank...with a plug going into the top of the "dome"..i thought it was just a coolant level sensor...not a ratio
  
  Drives me nuts...
  
  This morning..start car...flashing...go to gas station...turn off...start car...no flash...1 hour drive..no flash...go for lunch...flashes again....and so on....
• #3 by wolf_walker on 20 Mar, 2013 17:51
• I went through that years ago, freaked me out because I didn't have anyone to tell me it wasn't something terminal.
  The A2 sensor is cheap, need o-ring too, if you haven't changed your coolant with a good mix it might be warning you
  about something valid.
• #4 by Vohaul on 20 Mar, 2013 18:27
• Quote from: wolf_walker on 20 Mar, 2013 17:51

  I went through that years ago, freaked me out because I didn't have anyone to tell me it wasn't something terminal.
  The A2 sensor is cheap, need o-ring too, if you haven't changed your coolant with a good mix it might be warning you
  about something valid.
  

  
  I thought the sensor was part of the overflow tank itself?
• #5 by wolf_walker on 20 Mar, 2013 18:56
• Not in the 85 I had, dunno bout yours.
  
  Sent from my SCH-I535 using Tapatalk 2
• #6 by fatmobile on 21 Mar, 2013 20:42
•  Make sure the sensor has a good ground.
   If not, the voltage will go high and trigger the light.
   If you can pull back the rubber boot and measure the voltage drop accross the sensor while the engine is running it will tell you what the sensor circuit is seeing.
• #7 by Vohaul on 22 Mar, 2013 08:13
• mine doesnt have a rubber boot as far as i can tell...it has a hard plastic plug (with clips ) that goes into the top of the overflow tank
• #8 by fatmobile on 25 Mar, 2013 21:16
• So the wires connect to a hard plastic plug that disconnects from the sensor connector?
   Can you stick a volt meter to the wire ends while it's plugged in?
• #9 by Vohaul on 04 Apr, 2013 09:11
• Quote from: fatmobile on 25 Mar, 2013 21:16

  So the wires connect to a hard plastic plug that disconnects from the sensor connector?
   Can you stick a volt meter to the wire ends while it's plugged in?
  

  
  only if i strip a little insualtion off the wires going into the plug......ive been running it for 4 weeks now at 120km + a day with no issues.....one day the light flashes...next day it doesnt....temp guage is working and never goes above 1/2 way..and thats only if im in downtown traffic....which is normal...most days it doesnt go past 1/4
  
  on start up , thje light is off...usually after about 15-30 seconds, itll start flashing...if it hasnt turned on by then, it wont turn on the whole drive....