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  1. #1
    Registered Member Four Rings B6JoeS4's Avatar
    Join Date
    Sep 13 2008
    AZ Member #
    My Garage
    Terminator Cobra
    Chicago NW Burbs

    DIY: 3.0 G62 Green coolant temperature sensor

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    This is a DIY to replace the coolant temperature sensor on a 3.0 engine. You will often get a check engine light when this part fails and you will get the code 16500: Engine Coolant Temperature Sensor (G62): Implausible Signal. Or you may get 16502: Engine Coolant Temperature Sensor (G62): Signal too high.

    The part you need is the Green coolant temperature sensor. This is known as the G62 and they cost about $42 at the dealer where i got mine.

    You also may need the clip that holds the sensor in. its not necessary but i just replaced it. the parts guy at my Audi dealer said that sometimes they get brittle over time and it is best to just replace it. I paid $1.20 at my dealer but ECS has it for .56

    Tools you need: (note: these awesome tools are not mine, they are my friends tools)
    3/8" Ratchet with a swivel head
    5mm Allen head socket
    10mm Socket
    Philips screw driver
    Pick to remove the old O-Ring
    Clamp removal tool for clamps on intake hoses. (you can use vise-grips)

    First, unplug the MAF sensor that the red arrows are pointing to. Once you do that, you need to un-clip the MAF sensor from the air box. There is one clip that is circled, the other on is on the opposite side. Then remove the big clamp circled on the right and just slide it onto the accordion hose.

    Now pull the whole assembly off and set it somewhere where you wont step on it.

    Now you need to tackle this mess.

    First unplug this little guy. You should use a flathead and sort of work the hose off of its fitting. don't try to pull it. doing that will only make the hose tighter and you might rip it or break the check valve.

    Then unplug this thing, whatever it is

    The remove the thing you just unplugged. it comes off the same way a buckle does.

    Now remove the bolts holding on the plate. the allen by the fire wall is a 5mm, and the two bolts in front are 10mm sockets. Then you will be able to wiggle the plate out of there. I did it by sliding it to the passenger side.

    use a Philips and remove the clamp holding on the hose seen below

    There is one bolt holding on the tube leading into the throttle body. Use a 5mm allen head socket and a ratchet with a swivel head. you may be able to do this with a standard ratchet, but the swivel head is pretty much necessary. Its a very long bolt!!!!!

    this should give you a better idea of where the bolt is

    Now you should be able to pull the intake tube towards the firewall, then it should come right out

    the sensor is located on the passenger side, pretty much right by the passenger side head. You will see it. its green so it's hard to miss

    Unplug the harness on the sensor (i did not do this until later, bad idea) and then pull out the clip on the back side of it that holds it in. i wa sable to do it with my fingers.

    now pull the sensor out. i forgot if you have to turn it or not. be prepared for about 2 quarts of coolant to spill out.
    Use the pick tool to remove the old o-ring. chances are, it wont come off with the old sensor

    now put the new sensor in, this picture sort of shows the orientation; the flat side is facing the fire wall

    now slide the new clip in to hold it in place and put the harness on the new one. get your garden hose and give the area a good rinse to get rid of the spilled coolant

    Now go backwards int he DIY and install everything in reverse order.

    Fill up the coolant resivour and leave the lid open!!
    Start the car and set the climate control to HI. the blower does not need to be done. we are just doing this to get any air out of the heater core. hold the rpm's at about 2500 for a few minutes and watch for any bubbles in the resivour. when you see bubbles, you are purging air out of the system. when the bubbles go away, let the car idle for a few minutes. then, just to be sure, rev the engine a few times to get rid of any air pockets. I let the car idle for 10 minutes with the cap open while i was cleaning up. then i took it on a short test drive.

  2. #2
    Established Member Two Rings damionphillips's Avatar
    Join Date
    Feb 07 2007
    AZ Member #
    My Garage
    03 A4 3.0/87 e30 325is/00 RL

    Great pics. You cannot overstate how much of a pain in the ass this is if you have hands that are the size of a normal human. +1 to the accuracy of the info. Made my car stop sounding like a jet engine taking off upon starting...
    Currently swapping out the A/C controls for faster ones...

  3. #3
    Established Member Two Rings
    Join Date
    Jul 30 2007
    AZ Member #

    Thanks for the post... was invaluable in helping me replace my 3.0's coolant temp sensor.

    Things I might add...

    - it isn't necessary to remove the part of the air intake with the MAF on it, it takes a bit of shimming with the center-piece to get it off and back on, but was probably less work than actually removing the left part of the hose
    - if your car is cold, open up the coolant resevoir before starting work to release any pressure, then put it back on tight... that way when you remove the sensor you get minimal amount of coolant leaking out. I would say about a teaspoon or two was all that came out when the old sensor was removed
    I call 'em as I see 'em.

  4. #4
    Veteran Member Four Rings imnuts's Avatar
    Join Date
    Aug 12 2009
    AZ Member #
    My Garage
    Dolphin Grey Audi A4 3.0 Q 6MT

    Re: DIY: 3.0 G62 Green coolant temperature sensor

    I'm in the middle of trying to replace my sensor. First, I can't get the hard pipe out off the throttle body. There is a line that looks like it's hooked up to the vacuum system holding it in place. I can get to the sensor and have the cable off, but I can't get it out. I can rotate it about 1/16-1/8 of a turn, but that's all the movement it's doing. Am I pretty much just stuck trying to wiggle it more and more until it comes out?

    Sent from my Galaxy Note 2

    EDIT: I got it out after an hour or so on and off wrestling with it. I used a flash light and found that the rotation I was getting was just the green part of the sensor, the brass base was somewhat corroded in place. How I ended up getting it out was taking a small flat screw driver and using it to help pry up on the sensor while also pulling on it. Definitely a tight space to work in, especially when I couldn't get the intake tube/pipe off. Cleaned as much dirt and other crap out of the hole, removed the old oring, cleaned more junk out, then put the new oring, sensor, and clip in.

    One should definitely buy the new oring and clip with the sensor. My clip broke when trying to take the old one out. Needless to say, I hope the sensor lasts another 160k miles, because I don't want to deal with that again. Also, releasing pressure from the coolant system is a good idea. I only lost a few oz of coolant. Put a little bit back in the reservoir when I was done.
    Last edited by imnuts; 03-29-2013 at 12:53 PM.
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    3.0 JHM Tuned, JHM LWFW & Clutch, JHM Solid Short Shifter, Zingo Airbox Mod, quattro, Vogtland Jr. Suspension, Single Xenon E-Codes, Apikol Snub, 034 Motor & Trans Mounts

  5. #5
    Senior Member Three Rings 207carney's Avatar
    Join Date
    Apr 30 2012
    AZ Member #
    My Garage
    2003 A4 3.0Q 6MT

    Just did mine last night. Small pain in the ass. My 5mm allen socket was too wide and was able to just use a allen key and turn as hard as I could on the back of the intake tube. Also, after fighting for a few minutes to pull the sensor itself, I realized I had broken one half of the clip off, so check for that before you pull too hard. Releasing the pressure in the reservoir definitely helped keep coolant spill to a minimum.

    Great writeup, made this easy!
    2003 A4 3.0 Quattro 6MT | Air | The hole into which I throw my money
    1999 A4 Avant 1.8T Quattro 5MT | Static | Daily Turd
    iG @207carney


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