My check engine soon light has come on a couple times over the last few months, so took a minute to dump the fault codes today using the Ross-Tech cable.

I'm getting a:

5593 - Torque Management Request Input Signal A: Implausible P2545 00 [032]
- and -
5671 - Boost Pressure Regulation: Control Range Not Reached P0299 00 [104]

and then a series of Cylinder x: Misfire detected.

Is anyone familiar with these codes? How serious is the problem? The VCDS program indicates the frequency is 3, so I assume there's some ongoing issue (although check engine light is now off).

The 5671 sounds like it might be a turbo related issue. Ross-Tech diagnostic info indicates a possible problem with the Boost Pressure Control Valve. I'm curious whether a problem like this could lead to increased turbo lag - as I do believe there's a bit more hesitation than usual in taking off from a stop - but hard to be sure.

I had reported a similar problem (cylinder misfires - P0299, not sure of the Vag Com codes) when I had it in for my 25,000k maintenance. Audi service had diagnosed it as a cracked vacuum hose which they replaced. This sounds like it may be a similar issue.

Regardless, I have it booked in at Audi for a look next week and will take all the Ross-Tech (VCDS) reports with me to ensure they deal with the problem.

I'm not sure if this is typical, but my Audi service department doesn't seem to make use of the Ross-Tech diagnostic tools so I assume Audi dealers use proprietary diagnostic equipment vs. Ross Tech. There does seem to be some advantage to being able to document the fault codes, as I don't believe service departments spend any time researching codes that aren't reported by the customer (I expect they just clear the codes). In theory, fixing a problem early should reduce long term maintenance costs (i.e. when the warranty expires).

Thanks.

 

Resolved the problem with a full turbo replacement on the A4. There's been a bit of back and forth over the last couple months as they tried replacing all the valves etc. - but check engine light kept re-appearing.

A new turbo was brought in and they completed the replacement today. All is well so far.