Replacing the Transmission Control Module (TCM) $2500 ? -

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Old 07-29-2008, 04:53 PM
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Join Date: Jul 2008
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Default Replacing the Transmission Control Module (TCM) $2500 ?

I drive a 2004 Audi A4 1.8T CVT and recently my MIL (check engine light) came on. I went to the Audi dealer and they ran a diagnostic and they said I needed to replace my Transmission Control Module (TCM) and it would cost $2500 to replace it.

I got a copy of the diagnostic from them and the fault reads: "18201 P1793 Output Speed Sensor 2 ciruit No signal." The funny thing is that when I borrowed my friend's OBDII reader there was no faults registered and because there is no faults registered I can't clear the MIL (Engine Check) light.

Do you think I really need to pay $2500 and replace the TCM ?

Thanks for reading and any advice you can offer is greatly appreciated.

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Old 07-30-2008, 09:55 AM
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Join Date: May 2004
Location: Northern NJ USA
Posts: 4,035
Default RE: Replacing the Transmission Control Module (TCM) $2500 ?

You need a VAG code reader.
2009 Subaru Impreza 2.5i Auto 4dr Premium

Previous Car
2001 A4 1.8T Q Casablanca White, Tip, ESP, Xenon and Premium
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Old 07-30-2008, 12:01 PM
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Default RE: Replacing the Transmission Control Module (TCM) $2500 ?

If your Module is going bad, get it replaced before you screw up or weaken the transmission.
You can reset the drive cycle and continue to drive it. Just do not drive it in limp mode.
My best suggestion is to take it another Shop....NOT the stealership!
I just had to have mine replaced and with parts, labor, ect.... I paid $1600 at Eurosports.
Find a good certified Audi shop and have them check it out.
Also, it took 2 weeks to get the Module from Germany....
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Old 04-26-2009, 09:54 PM
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Join Date: Apr 2009
Posts: 1

hey im from australia and im having the same TCU problem where are you guys from? and do you know anywhere in Australia that will do it for cheap? thanks
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Old 03-06-2012, 10:38 AM
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Join Date: Mar 2012
Posts: 16

I purchased an Audi repair manual from eBahn for my 2003 A4 Cabriolet when new. It has been well worth the outlay since it helps me know how to take off door panels, has location of components and repair procedures as well as technical bullentins. Because of the components location, I was able to replace the coolant sensor and would have not looked in the area where it is.

When my Transmission Control unit flashing display came on, I began to do my research (and have posted some information (and a slight rant) on this site). I am dissappointed in Audi's lack of responsibilty toward the CVT and it's electronic control unit, which obviously has flaws.

In answer to your question, if the PRND is flashing, it is the component inside the transmission (the TCU) that is flawed). Audi would like for you to return it to the dealership for replacement, of which the repair bill will shock you. After market shops seem to be around $2,500 total, with the unit at a price of anywhere from $1,100 to $1,500.

There are providers on e-bay that will repair YOUR unit for $350 to $500. A couple guarantee the component for lifetime and you will NOT have to get the dealership involved to obtain a code from Audi of Germany.

The manual I have refers to the flashing light and indicates the car can be driven for a few miles with no problem. If continued, the transmission control unit may generate signals that can interfere with the performance of the transmission. The manual indicates that problem that can occur are the transmission shifting to neutral (and you can't change it out of that) or the potential of locking up or... further the transmission being complete destroyed.

So, the short answer is address the flashing PRND. The code reader you used may only read the Engine codes and not the transmission codes...thus the flashing PRND light indicator versus the ENGINE light indicator, which may read other components.
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Old 03-19-2012, 11:40 PM
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Join Date: Mar 2012
Posts: 8
Cool TCM replacement instructions

Can anyone help with instructions on replacing the TCM on a 2003 A4 1.8T FWD CVT?

So far i understand the unit is located in the trani and it can be accessed by removing the trani oil pan and draining the trani fluid

Besides the obvious trani oil, do i need to get anything else like a oil pan gasket or anything else before starting this job? Anything in particular to be watching for when pulling it out?

I have a friend that is a licensed mechanic and will do this for me so I can ship the damn unit to Toronto, i found a company that fixes them for 300 and sum dollars (which is way cheaper then what the dealer wants 2K plus!)

Any help or advice is much appreciated
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Old 03-20-2012, 01:45 PM
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Join Date: Mar 2012
Posts: 16

I can send the instructions from my e-bahn audi repair manual. Mine is a 3.0 liter, but I imagine the transmission process for replacing the TCM is the same.

I tried to send it via this e-mail, but the size is bigger than the forum allows.

Hope that helps. Richard
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Old 03-20-2012, 02:07 PM
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Join Date: Mar 2012
Posts: 8

Thanks Ritchie that would be great! Can you email it to me please at

hopefully they are in the same spot and I will let you know once I read it.

Much appreciated brother!
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Old 03-20-2012, 02:41 PM

Join Date: Apr 2011
Location: Beaverton Oregon
Posts: 511

Here is where the TCM is located, more from the tail shaft housing area than the pan. These #35's (plus gaskets, O rings and bolts) must be ordered from Audi off the cars vin#. Once installed it has to be programmed by your dealer also.

Click the image to open in full size.
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Old 03-20-2012, 03:26 PM
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Join Date: Mar 2012
Posts: 8

Thanks Jeff; the detailed trani info helps locating the TCM but I was just looking for someone that has taken it out before, with instructions on do and donts.....or Ritchards manual instructions should do it.

By the way and as mentioned in the original post, i found a way to avoid going to the dealer (sorry if you are working for one!) and i dont have to buy a new TCM. I found a company that can fix it, afterall is just a computer chip. THis company can fix your exsisting TCM thus eliminating the need to re-code it when you put it back in....and they life time guarantee it.

Now all i have to do is go to my mechanic with specific instructions how to pull the TCM out so i can ship it to get it fixed. He is pretty good but we just want to make sure we cover all the bases and the Audi forum has all the pros around.
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Old 07-16-2012, 05:31 PM
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Join Date: May 2009
Location: San Juan, Puerto Rico
Posts: 24
Default TCM bad

I have an 2003 audi 1.8t can somebody tell me where is the TCM located? Is it inside the transmission???
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Old 07-17-2012, 10:51 AM
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Join Date: Mar 2012
Posts: 8

is it the FWD or the Quatro?

On the 2003 A4 1.8 T FWD the TCM is located at the back of the trani (unlike the Quotro where it can be found under the driver side floor pad)

If it is the FWD, then you have to drop the trani, drain the fluid to access the TCM.

A mechanic pulled it out for me (and after it was fixed, placed it back in) for $200. I sent the TCM to a company in Toronto that will actually fix the part (its just a computer chip afterall), they offer lifetime warantee on thier fix and it only costed $350 plus tax......i changed the trani (recommend) fluid while we were at it $150 worth of expensive fluid.

Math: $200+$400+$150 = $750

Dealership quoted my $1,900 for this I saved myself $1150!

Car works like a charm now....I sold it to a buddy of tired of the bs "german engeenering" machine that gave me nothing but head aches.

I have a mitsubishi now...fine japanese rice burner that is a tank and 4 years later 150000km and I havent touched the engine.

Good luck
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Old 07-17-2012, 10:57 AM
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Join Date: Mar 2012
Posts: 8

BBA -Remanufactoring fixes your tcm for about $350 plus tax

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Old 09-18-2012, 04:18 PM
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Join Date: Dec 2008
Posts: 19

I though the module was under the windshield, my car is driving in auxiliary mode and I was hoping to fix it myself, found one for $70 with a one year warranty. Any opinions on this?
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Old 04-25-2013, 03:31 AM
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Join Date: Apr 2013
Posts: 1

I am interested to learn how the replacement/rebuild of your TCM turned out. My sons car is now flashing the PRNDS. I just bought him a used 2003 A4. Three days later the flashing started. Hope to learn from you and save money on the repairs.
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Old 04-25-2013, 11:31 AM
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Join Date: Mar 2012
Posts: 16
Default Tcm

This is one of the worst things about Audi. The CVT transmission is totally controled by the Transmission Control Module. When they came out with the CVT, it was the "greatest thing since sliced bread", but it came out with problems. The early models have flaws in the TCM and, sure enough, go bad and have to be replaced.

Of course, Audi does not acknowledge this flaw. However, the dealership sure enjoys the flaw because of the revenue.

The TCM is mounted in the transmission. It can be removed from the back of the transmission without lowering the transmission, however, there is a support bracket that has to be removed and taken out of place to get at the TCM cover and TCM. The TCM is not that big and has "arms", so care should be taken in the removal and installation process.

The $2,500 estimate is about right at a dealership. The good news is that the dealership will have to make it "right", versus a local shop that may not be as familiar. In my case, I did NOT use the dealership. I had a local shop remove the TCM, sent it to Xemodex in Canada, they re-programmed the component, then I had it reinstalled. This can be done for much less. The module re-programming is about $350. The removal of the TCM is about $200to remove and the same to re-install.

When the TCM begins to provide the alert check engine light, you should take action. If you wait, there are potential problems that begin to arise. First, the car will not want to shift into reverse. It will eventually, but is slow. If you continue, the module can send eroneous information to the transmission and, yes, ultimate total destruction of the transmission can occur. Not a good situation.

I have the shop manual on my car, so I have the documents about how to remove the TCM, etc.

My car is a 2003 A4 Cabriolet, 3.0 with the CVT. I have come to hate my car and the responses from Audi. I bought the car new and seem to have had things go wrong every few months since new...many small, several major.
I went back to BMW...totally satisfied.

I hope I have helped you some.
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Old 09-23-2014, 07:39 PM
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Join Date: Sep 2014
Posts: 1
Default Audi A4 2008 / Transmission control flashing/engine light on and off

Hey Guys !
I have a little problem with my Audi A4 2008
The transmission range sensor or the circuit range / performance or the TCM
My PRDS is flashing at some point and my engine light goes on and off at some point... Any ideas what could be the real problem ? I am going to see the dealer in 2 days in order to know exactly but I don't know how much it will cost metro get it all fixed, any suggestions ??? Even if I have to see some other shop in boston Ma... Thank you.
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Old 09-24-2014, 11:18 AM
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Join Date: Mar 2012
Posts: 16
Default Cvt

You're not going to like the answer.


Read through previous threads on this topic since I was one that posted several. When the gear dash light (Park, Reverse, Drive) starts flashing, it is indicative of the problem with the Transmission Control Module of the Continuously Variable Transmission.

While the transmission was touted as "fewer moving parts and high degree of reliability"...they were wrong. The early versions of the CVT, of which I had a 2003 Audi A4 Cabriolet, are now showing the problems. The TCM will have to be replaced and then the new transmission TCM re-programmed.

Do not go very long. If not addressed, the transmission can actually destroy itself. You will likely notice the transmission not engaging very quickly when shifting into reverse...then unusual shifting when going forward.


You won't like the solutions either. There was a class action law suit against Audi for the TCM problems. It was settled and Audi agreed to fix or reimburse for costs associated with this problem, but, as you might expect, it had conditions. One of which was that the car had to be under 100,000 miles. Naturally, most of the TCM problems occur just under that and of course over 100,000 miles. Many people, including me, were screwed and had no relief for the cost.


You basically have two choices.

1. Go to the dealership. They will likely charge you between $2,500 and $3,000. They will fix it correctly since they have multiple bulletins on the topic. They replace the TCM and re-program

2. You can check with a local shop to have the TCM removed and there is a firm in Canada that will re-program the TCM and then you can have it re-installed. They guarantee their work and guarantee the re-program corrects the problem. That is what I did. The cost is about $300 to have it re-programmed and you can decide if you have the time to allow the TCM to travel by regular mail to them or overnight up and back...which can easily add about $100. The TCM has protruding parts (fingers) that are sensors.
So, the TCM has to be extracted a bit carefully, but for sure, inserted correctly. If you need the firm name in Canada, I can get it from my maintenance file, but don't have it at the office today. You can probably Google the TCM re-programming and locate them.

I hope the information was of some help.
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Old 05-03-2015, 03:36 PM
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Join Date: May 2015
Posts: 1
Default replacement video

Hi, I found this video on replacing my tcm on my 2004 Sebring. looks simple enough that I could probably do it myself. here is the link. hope it helps you because it is going to save me a lot of money. good luck
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Old 05-04-2015, 08:39 PM
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Join Date: Apr 2015
Location: Lake Elsinore CA USA
Posts: 3
Cool A4 b6 cvt tcm

Has anybody sent a TCM to this servicer, they repair your unit and program it, thanks

Known problems:

- BLINKING PRNDS indicator

Considering the massive amount of 2005 to 2008 AUDI's with CVT transmission TCM failures, we perfected a REPAIR KIT that will completely restore your TCM for these known problems.

We do repair both types of those modules - those with a round and rectangular plug.

You will send us your bad CONTROL MODULE. We will install the REPAIR KIT, make necessary repairs on the circuit board, perform a final test and return it to you.
No additional programming is required.

Procedure takes 1-2 bus days.
Not all modules are repairable, and unfortunately, some of them damaged beyond the repair point.

This is your mechanic's responsibility to pinpoint the problem in the Transmission Control Module.

The range sensor itself, valve body and wiring must be tested for possible failures.

We do not diagnose the problem over the phone!

For years and thousands of those modules repaired we have practically no warranty returns.

Removing-Installation instructions for DIY available, email me after buying this service, but it's recommended to do the replacement in a professional mechanic shop, as the transmission needs to be lowered and tail cover removed to get access the TCM.

Non-repairable modules, or modules with no repairs needed will be returned to you for the shipping cost.

Please, pack it very well ( we recommend to double box it),
include copy of your Paypal payment to identify yourself and send to:

5911 Lemona Ave
Van Nuys, CA 91411

You pay shipping to send it to us, we pay shipping to send it back. Priority mail with delivery confirmation included in the price. Optional overnight is available during checkout.

Repairs done to Your Transmission Control Module covered with LIFETIME warranty .
Dealer price is around $2500 for the TCM and installation.

We need and expect you to read the listing for "How It Works" and all general questions,
please only dial 818-429-4889 if your question wasn't already answered.
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