DIY: 3.0 G62 Green coolant temperature sensor

[B6JoeS4]

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.

[damionphillips]

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...

[pr0digy30]

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

[imnuts]

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.

[207carney]

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!

[arjun90]

How do you reinstall the accordion hose on both sides? I'm having a hard time putting the hose back in place. Do I need to spring back the clamps towards the middle of the hose?

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.

[Lornnn]

hey guys, i did this today and just a heads up that you do not need to separate the valves/vaccum lines/wires/etc or otherwise fully remove the black panel in this photo:



you just need to remove the 3 bolts so the panel can detach from the intake elbow and wiggle around while you remove the 5mm allen bolt holding the elbow to the throttle body.

if you look/work from the passenger wheel side of the engine bay you'll be able to get your allen bit or key in there to remove the bolt and wiggle the elbow out without too much trouble.

worked well for me, and might save you the time and trouble of messing with all of those little connections and such on top of the panel.

[wisconsinbrew]

Did this today on a 2004 A4 Avant 3.0 Tiptronic with 100,180 miles on it.
Great DIY guide. Just a few observations that may help others in the future.

I echo what Lornnn said above about the panel held down by 3 bolts. Just remove the 3 bolts and slide the panel about 1/2' - 3/4" towards the intake manifold. Mine had (3) 10mm bolts holding it down.
The 5 mm allen head bolt securing the intake elbow is not removed, it comes out about an inch and you can feel when it is no longer grabbing the threads. I was able to use a 1/4" drive socket with a very short extension and a socket with a 5mm allen bit taped in place. Worked fine.
Flat head screwdrivers are your friend.
I used a small flathead to help pry the rubber tube from the fitting on the intake elbow.
I used a larger flathead to help pry the intake elbow off.
I used a flathead along with a pliers to pull and wiggle the sensor out. It comes straight out using that combination along with some patience and a few minutes. Possibly some swearing...
I removed the cap from the coolant overflow reservoir and i had about 1/2 cup of coolant escape when removing the sensor.

Green four contact sensor, with clip and o-ring in the box was about $13 at O'Reilys and comes with a lifetime warranty. Not having the stealership rape me for diagnosis, parts and labor, priceless.

[Turbo510]

This DIY guide from 8.5 years ago was well-done. My only observation is that the coolant instructions are not ideal. First, as mentioned in later responses, the reservoir cap should be opened to dump any residual pressure, then put back on. However, I used a piece of Saran wrap in place of the cap, held with a rubber band to ensure the reservoir was sealed. Second, if you suspect that air entered the cooling system, the proper way to clear it out is at the bleeder screws and the vent hole in the heater hose, not by revving the engine. Also, the instruction to set the climate control to High is a waste of time; there being no heater valve, there is nothing to be gained by doing that.

[AudiTLC]

Thank you B6Joes4 for the writeup!
This was maybe a 20 min job, and very simple with this diy.
-The platform at the top of the intake- i just removed the 3 bolts. No need to take apart anything. I just disconnected one vac hose to move the assembly over a bit.
-the flex head socket was essential for me, thanks for that tip. The bolt doesnt require much torque, it's just a tricky reach to get to.

I have the same car as you, and wanted to thank you for the tip on using flatheads everywhere- just makes life easy!

Did this today on a 2004 A4 Avant 3.0 Tiptronic with 100,180 miles on it.
Great DIY guide. Just a few observations that may help others in the future.

I echo what Lornnn said above about the panel held down by 3 bolts. Just remove the 3 bolts and slide the panel about 1/2' - 3/4" towards the intake manifold. Mine had (3) 10mm bolts holding it down.
The 5 mm allen head bolt securing the intake elbow is not removed, it comes out about an inch and you can feel when it is no longer grabbing the threads. I was able to use a 1/4" drive socket with a very short extension and a socket with a 5mm allen bit taped in place. Worked fine.
Flat head screwdrivers are your friend.
I used a small flathead to help pry the rubber tube from the fitting on the intake elbow.
I used a larger flathead to help pry the intake elbow off.
I used a flathead along with a pliers to pull and wiggle the sensor out. It comes straight out using that combination along with some patience and a few minutes. Possibly some swearing...
I removed the cap from the coolant overflow reservoir and i had about 1/2 cup of coolant escape when removing the sensor.

Green four contact sensor, with clip and o-ring in the box was about $13 at O'Reilys and comes with a lifetime warranty. Not having the stealership rape me for diagnosis, parts and labor, priceless.

[Rejoice]

This DIY guide from 8.5 years ago was well-done. My only observation is that the coolant instructions are not ideal. First, as mentioned in later responses, the reservoir cap should be opened to dump any residual pressure, then put back on. However, I used a piece of Saran wrap in place of the cap, held with a rubber band to ensure the reservoir was sealed. Second, if you suspect that air entered the cooling system, the proper way to clear it out is at the bleeder screws and the vent hole in the heater hose, not by revving the engine. Also, the instruction to set the climate control to High is a waste of time; there being no heater valve, there is nothing to be gained by doing that.

Could you possible show a picture of the bleeder screws and vent holes you are referring to? Do you idle the car with them open or do you just need to open them?