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Audi A6 C5 1997-2004: Torque Converter Diagnostic

The torque converter in the Audi A6 automatic transmission features a lock up clutch to provide better fuel economy and performance. When an internal seal fails, the lock up function doesn't work and your transmission is on borrowed time.

By Jeffrey Smith - July 18, 2016

This article applies to the Audi A6 C5 (1997-2004).

One of the more common and evil diagnostic errors you may find with your Audi is the P0741 code, which means that your clutch torque converter is not locking up. If you are extremely lucky, it may just be a result of old and dirty transmission fluid. If you are unlucky, this means that the seal inside your torque converter is shot and the entire converter will need replaced. This is not a DIY job for most home grown mechanics with basic tools. It is a very labor intensive job that requires a lift to do right, a transmission jack, and removal of the entire transmission. Audi did release a couple of technical service bulletins (TSB) that addressed this issue (TSB 32-05-02 and TSB 32-07-01). There are two opposing views among forum posters with a bad converter. On one side, you will hear that it will be fine just leaving it alone and performing regular transmission fluid flushes, possibly with every oil change and hoping for the best. Another side will argue that the bad TC will create excessive heat, which will result in quicker wear of other components in your transmission. You can expect to pay at the minimum $2,500 to have the TC replaced at an independent shop, and much more if you take it to the dealer, and most of that is labor. Read on and we'll help you determine just how bad things are in your A6 transmission.

Audi A6 C5 1997-2004: Torque Converter Diagnostic

Materials Needed

  • Replacement transmission fluid
  • Transmission fluid additive
  • Replacement TC
  • Lift or tall jack stands
  • Hydraulic floor jack
  • Transmission jack

Step 1 – Flush the transmission fluid

Infrequently, dirty transmission fluid can cause the TC to stick and a good flushing can remedy the situation.

Dirty or very old transmission fluid loses its lubrication properties, and viscosity. Since the transmission works by pumping fluid pressure into various parts, lower or higher viscosity fluid can change the way it shifts, and affect the lock up of the converter. You might just be lucky, and a full transmission flush with high quality transmission fluid can solve your problems. Similar symptoms can also be caused from low fluid levels, which don't allow the pump to get a good supply and pressure. In either case, flush your transmission fluid and use a good fluid replacement like genuine Audi or Ravenol. For more information on fluids, filters and flushing it, check out the how-to at Bluaparts.com.

Flush that old transmission fluid before contemplating a new TC.
Figure 1. Flush that old transmission fluid before contemplating a new TC.

If your flushing didn't help, there are some other thing you can look at before jumping right to the TC.

Step 2 – Check your valve body

If you have diagnostic tools to check your transmission, you may find the problem is in the valve body.

If your converter clutch isn't locking, you may need to replace your valve body. This isn't the cheapest repair, but it is a lot cheaper than dropping your engine and transmission to get to the torque converter. It is much less labor intensive and you can do this job on your own in your garage with a floor jack and some jack stands. It is sometimes recommended to replace the valve body if you replace the torque converter, as there may be contaminated fluid in the passages of the valve body that are nearly impossible to get fully clean.

The valve body might be the actual problem rather than your torque converter and is a far easier replacement job
Figure 2. The valve body might be the actual problem rather than your torque converter and is a far easier replacement job.

If a new valve body didn't fix the code, you will need a torque converter after all.

Related Video: How to Remove Automatic Transmission Valve Body

Step 3 – Replace your torque converter

Your P0741 code almost always indicates a failed torque converter and there is usually no other option.

The torque converter isn't an easy repair. For the DIY mechanic, you'll really need a lift and a transmission jack. There are some who argue that the engine does not need to be dropped, but that is how the pros do it, which makes this job really costly. The process isn't easy to do on your own, but it is doable if you have the tools and time, and you'll save yourself a great deal of cash.

  • You'll need to remove your exhaust system.
  • Unmount the rear driveshaft.
  • Remove the heat shield and the front axles.
  • Detach the shifter cable to the transmission.
  • Disconnect the wiring harness on the front of the tranny.
  • Remove your speed and RPM sensors.
  • Some cars have an access port on the bell housing to remove the torque converter bolts, which will save you from removing the alternator and starter.
  • Remove the motor mount nuts and the transmission mounting bolts.
  • Put your transmission jack in place.
  • Remove the mounting bolts.
  • Lift the motor slightly to get to all of them.
  • This is where a pro will just drop the entire motor, making this a little easier.
  • Once the transmission is out, you cam remove and replace your torque converter.
Replacing your torque converter (1) is likely the only option to resolve your P0741 issues
Figure 3. Replacing your torque converter (1) is likely the only option to resolve your P0741 issues.

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