2006 audi a4 coolant temp sensor

2006 audi a4 coolant temp sensor
12-18-2012, 01:55 PM

Join Date: Feb 2011

Posts: 7

2006 audi a4 coolant temp sensor
DIY: B7 Audi A4 2.0T FWD Coolant Temp Sensor (CTS)


If you're getting a P2181 code its possible you need to replace your CTS. It seems like these things go bad all the time. Here's a cheap and easy DIY:


DIY for B7 Audi A4 2.0T FWD Coolant Temperature Sensor (CTS)

Here�s what you need:

Part # 06A919501A � Coolant Temp Sensor (GREY 2 pin)
Part # N90316802 � O ring
Part # 032121142 � plastic retaining clip
Flat head screw driver
Flashlight
Mirror

Step 1: Wait until the engine is very cold. You�ll be working behind the engine block near the cat and it gets pretty hot. Remove Engine Cover.

2006 audi a4 coolant temp sensor

Step 2: Use a flashlight and mirror to get a visual on the CTS.

2006 audi a4 coolant temp sensor

2006 audi a4 coolant temp sensor

Step 3: Insert a flathead screwdriver into the small opening (indicated by the arrow above) on the electrical connector and gently pry up. Remove electrical connector and move it out of your way.

Step 4: Insert a flathead screwdriver into the small opening (indicated by the arrow above) under the plastic retaining clip and gently pry up. Remove plastic clip and try not to drop it. You may need it as back up later.

Step 5: Gently pull out the old CTS. Some coolant will come out but not too much. Locate and set aside the old O-ring on the top of the sensor. If you can�t see it, it�s up inside the plastic pipe where the CTS sits. Reach in there and pull it out. You may need it as back up later.

Step 6: Place new O-ring on top side of the new CTS and insert electrical connector into new CTS. Firmly push new CTS into the plastic pipe where the coolant came out. You do this pretty much blind so you have to feel around and make sure the new CTS is seated correctly.

Step 7: Place new plastic retaining clip into clip grooves until it clicks into place. This is somewhat difficult and frustrating because you have to keep the CTS seated correctly while orienting the clip to click into place in the grooves. You do all of this blind. It took me about 20 minutes to finally get it. If you drop the new O-ring or new plastic clip in the process, it�s possible it will be tough to find or retrieve from behind the engine block. Obviously you can use the old ones if this happens.

That�s it!

2006 audi a4 coolant temp sensor
03-09-2013, 04:54 PM

2006 audi a4 coolant temp sensor

Join Date: Sep 2009

Location: Central Valley CA

Posts: 100

2006 audi a4 coolant temp sensor


Dude, super write up, great pics and accurate! thanks!!!
I assumed my CTS needed replaced based on the P2181 but after changing it out, the same code again has reappeared; therefore i will change out the thermostat.
Have you done this yet and or is there a write up you can show me or provide the link for a DIY?

Thanks again!
Rich

2006 audi a4 coolant temp sensor
03-10-2013, 10:17 AM

Join Date: Feb 2011

Posts: 7

2006 audi a4 coolant temp sensor
Audi A4 B7 2.0T Thermostat replacement


Quote:

Originally Posted by rhohmann

2006 audi a4 coolant temp sensor

Dude, super write up, great pics and accurate! thanks!!!
I assumed my CTS needed replaced based on the P2181 but after changing it out, the same code again has reappeared; therefore i will change out the thermostat.
Have you done this yet and or is there a write up you can show me or provide the link for a DIY?

Thanks again!
Rich

Rich: Yes I replaced my thermostat a couple months ago so it fresh on my mind. Happy to answer any questions or help out where I can. It was basically my first (other than the CTS) DIY I've ever done so you can definitely handle it. Not too bad, but takes some patience. Try the link below. Its for a A4 1.8T but its pretty similar.

try this link, lemme know if it doesn't work for some reason:

https://docs.google.com/file/d/0B2dG...it?usp=sharing

Here are some tips:
(1) Get this: Home Page > Search > 06D121111G2KT > ES#2586519 Thermostat Replacement Kit - 06D121111G2KT

(2) One of these makes life way easier:

(3) This came in handy as well. But not totally necessary :

(4) you ABSOLUTELY need one of these

(5) you don't need to remove throttle body (as described in the above link)

(6) you might need a buddy to get the bottom quick connect hose off. We used a rubber mallet/hammer and a screwdriver. One guy held the quick connect hose, other guy tapped the top of the connect with the screwdriver/mallet until it finally popped off. This is probably the only semi-difficult part about the job.

(7) drain your coolant before hand.

(8) a torque wrench is a "nice-to-have" for installing the new thermostat, but not totally required.

(9) need an 8 or 10 mm hex bit to remove the alternator, need a long 17 mm box end wrench to get the serpentine belt off

(10) might need to replace the O-ring on the middle hose. I think its this Home Page > Search > N90316802 > ES#264172 Sealing O-Ring - Priced Each (19.6x3.6mm) - N90316802 but I'm not totally sure.

Hope this helps. Feel free to PM me if you have any other questions.

2006 audi a4 coolant temp sensor
03-10-2013, 07:44 PM

2006 audi a4 coolant temp sensor

Join Date: Sep 2009

Location: Central Valley CA

Posts: 100

2006 audi a4 coolant temp sensor


Holy crap, I don't think i want to do this.
I saw another vid of a dude replacing his thermostat on a 1.8 also but it was a more traditional thermostat than what i just viewed, and it was located near the bottom of the block near the radiator; and it looked rather easy unlike this large thermostat housing.
Rich

2006 audi a4 coolant temp sensor
03-11-2013, 01:17 PM

Join Date: Feb 2011

Posts: 7

2006 audi a4 coolant temp sensor


To each his own. Like I said, I did it with zero experience so it's certainly doable. I got a quote for $500 from my mechanic to do the job.

2006 audi a4 coolant temp sensor
03-17-2013, 08:35 AM

Join Date: May 2010

Posts: 685

2006 audi a4 coolant temp sensor


CTS is a good first part to throw at P2181, but it's more likely a thermostat with that code. I had my temp sensor replaced, but the code came back, so I got a local German specialist shop to do my t-stat for about $350 (well worth it considering the part is about $80 and it would have probably taken me all day to do it). The dealership quoted me $500 and I laughed at them.

2006 audi a4 coolant temp sensor
12-14-2014, 03:42 PM

Join Date: Dec 2014

Posts: 2

2006 audi a4 coolant temp sensor


Thanks for the great instructions and photos. One thing I want to add is about the O Ring. Once I pulled out the sensor and the coolant started to flow.. I noticed the O Ring was not on the sensor. Before searching all around the engine compartment, I stuck my finger up in where the sensor goes. The O Ring was stuck up in there still. I'd recommend checking to make sure it's not in there, when putting the new sensor back in. I'm assuming with double O Rings, it'll leak, and you probably won't even get to put the retaining clip back in place.

Very easy process. Took me literally 8 minutes.

2006 audi a4 coolant temp sensor
01-04-2017, 11:54 AM

Join Date: Jan 2017

Posts: 3

2006 audi a4 coolant temp sensor


Quote:

Originally Posted by MoxUSC

2006 audi a4 coolant temp sensor

If you're getting a P2181 code its possible you need to replace your CTS. It seems like these things go bad all the time. Here's a cheap and easy DIY:


DIY for B7 Audi A4 2.0T FWD Coolant Temperature Sensor (CTS)

Here�s what you need:

Part # 06A919501A � Coolant Temp Sensor (GREY 2 pin)
Part # N90316802 � O ring
Part # 032121142 � plastic retaining clip
Flat head screw driver
Flashlight
Mirror

Step 1: Wait until the engine is very cold. You�ll be working behind the engine block near the cat and it gets pretty hot. Remove Engine Cover.

2006 audi a4 coolant temp sensor

Step 2: Use a flashlight and mirror to get a visual on the CTS.

2006 audi a4 coolant temp sensor

2006 audi a4 coolant temp sensor

Step 3: Insert a flathead screwdriver into the small opening (indicated by the arrow above) on the electrical connector and gently pry up. Remove electrical connector and move it out of your way.

Step 4: Insert a flathead screwdriver into the small opening (indicated by the arrow above) under the plastic retaining clip and gently pry up. Remove plastic clip and try not to drop it. You may need it as back up later.

Step 5: Gently pull out the old CTS. Some coolant will come out but not too much. Locate and set aside the old O-ring on the top of the sensor. If you can�t see it, it�s up inside the plastic pipe where the CTS sits. Reach in there and pull it out. You may need it as back up later.

Step 6: Place new O-ring on top side of the new CTS and insert electrical connector into new CTS. Firmly push new CTS into the plastic pipe where the coolant came out. You do this pretty much blind so you have to feel around and make sure the new CTS is seated correctly.

Step 7: Place new plastic retaining clip into clip grooves until it clicks into place. This is somewhat difficult and frustrating because you have to keep the CTS seated correctly while orienting the clip to click into place in the grooves. You do all of this blind. It took me about 20 minutes to finally get it. If you drop the new O-ring or new plastic clip in the process, it�s possible it will be tough to find or retrieve from behind the engine block. Obviously you can use the old ones if this happens.

That�s it!

That's a great write-up, thanks. Do you know if the cts is accessible from below?

2006 audi a4 coolant temp sensor
01-05-2017, 02:38 PM

Join Date: Feb 2011

Posts: 7

2006 audi a4 coolant temp sensor


Quote:

Originally Posted by Vic Flange

2006 audi a4 coolant temp sensor

That's a great write-up, thanks. Do you know if the cts is accessible from below?

I wasn't able to access from below but I also did not have a lift and it was my first DIY. Good luck!

2006 audi a4 coolant temp sensor
01-05-2017, 02:41 PM

Join Date: Jan 2017

Posts: 3

2006 audi a4 coolant temp sensor


Quote:

Originally Posted by MoxUSC

2006 audi a4 coolant temp sensor

I wasn't able to access from below but I also did not have a lift and it was my first DIY. Good luck!

Thanks! I wish I had a lift! I'll drive it up onto ramps and see how that goes.

Where is the coolant temperature sensor located on an Audi a4?

Figure 1 The coolant temperature sensor is located on the lower left side of the cooling system. It is on the lower left hose coming from the radiator (red arrow). The coolant fluid will drain out when you remove it so be prepared to either catch the coolant and reuse it or properly dispose of it.

What happens when the coolant temperature sensor goes out?

If the coolant temperature sensor malfunctions, it can transmit a false signal to the computer. And the response of the computer may unbalance the timing and fuel calculations. It is also common for a coolant temperature sensor to fail without warning and send permanently cold signals to the computer.

What are the signs of a failing temperature sensor?

7 Symptoms of a Bad Coolant Temp Sensor & Cost to Fix.
Check Engine Light..
Engine Overheating..
Poor Fuel Economy..
Poor Engine Performance..
Broken Water Pump..
Control of Cooling Fan..
Black Smoke From Exhaust Pipe..

Where is the coolant temperature sensor located?

The coolant temperature sensor will be located directly behind the coolant pipe. In most modern cars and vehicles, this is present behind the right cylinder head that is located right underneath the air intake pipe.