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Audi A6 C5: What's Wrong with My Steering?

The A6 is a luxury sports sedan that relies on modern conveniences to give it a sporty and comfortable ride, but when a system fails, like the power steering, it is no longer fun to drive.

By Ryan Christian - April 22, 2016

This article applies to the Audi A6 C5 (1998-2004).

Power steering in your A6 is what lets you have wide sticky tires, and effortless parking, all in one car. When you turn the wheel, the tires move without too much struggle on your part, and that's the way you like it. What do you do then when the power steering isn't working quite like it used to? In this article we'll explore what could be going wrong, and ensure that turning your wheels is no longer a workout.

The advanced Audi A6 front suspension and steering
Figure 1. The advanced Audi A6 front suspension and steering.

Step 1 – Check your fluid

Your power steering fluid may be low, dirty, or incorrect, resulting in heavy steering.

The most basic problem that the power steering system have is low fluid. In the power steering system no fluid means no function, and in Audis, not using the proper fluid to fill up when it is low can quickly lead to more problems. More often than not making sure the fluid is full, clean, and the proper specification in the first place can solve a power steering problem.

  • Check the power steering reservoir to be sure that the fluid level reads correctly on the side of the reservoir.
  • Correct Audi fluid should be greenish in color.
  • If the level is good, make sure the fluid is clean and not cloudy or black. If it is black, you will need to do a flush and change the old fluid, as described here: How to Change Power Steering Fluid and Bleed.
  • If it does need to be added, be sure to use only VW/Audi G00200 spec, or Pentosin CH11 power steering fluid.
  • Look for the fluid level on the side of the reservoir
    Figure 2. Look for the fluid level on the side of the reservoir.
  • If the fluid is made in German, that is a good sign
    Figure 3. If the fluid is made in German, that is a good sign.

Pro Tip

Using any fluid other than Audi's specific fluid can harm your power steering pump. The fluid's composition is different from what most cars use and problems have been known to occur when anything else is used. If your fluid isn't stamped with the four rings or VW, don't use it.

Step 2 – Check the steering assist module

The electronic steering assist relay may be broken and in need of replacement.

Every A6 is equipped with an electrical steering assist relay to help the power steering system operate properly. If this relay is broken, your power steering can act up, making your power steering intermittently heavy.

  • Scan for codes with VAG-COM. If the system says you have no steering assist module, this is an indicator that your relay is broken and in need of replacement.
You will need a VAG code scanner to check for the broken relay
Figure 4. You will need a VAG code scanner to check for the broken relay.

Step 3 – Check your power steering rack

Your power steering rack could be bad and in need of replacement.

The power steering rack is one of the most important parts of the steering on any car, and if you know your fluid is good and the relay is functioning, this may be your culprit. There are valves on the inside of the rack that may begin sticking, and when that happens, the system will be unable to assist one or both sides of the power steering rack.

  • Check under the car for leaking power steering fluid.
  • Double check that the problem is only occurring in certain steering positions. This is a clear indicator of a power steering rack problem.
The typical Audi steering rack with variable assist
Figure 5. The typical Audi steering rack with variable assist.

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