Hi everyone,

I’m hoping to get some guidance before I make an expensive mistake.

I’m currently in Bogotá, Colombia, and the reality here is that many workshops tend to jump straight to major repairs (especially anything involving the PDK/mechatronics) without a proper diagnostic process. Parts availability is limited, labor quality is inconsistent, and once something is opened, there’s no easy way to undo it. That’s why I’m trying to be extremely methodical before authorizing any work.

Vehicle:

2015 Porsche Macan S

32,000 miles

Original owner

Background / Recent Change:

• Battery was just replaced 2 days ago

• Previous battery was original (~12+ years old)

• Start/Stop system had stopped working prior to replacement

Issue:

• On cold start, I get a warning that reverse gear is not available

• After a short period, as the car warms up, the issue disappears completely

• Once the warning is gone, the car drives perfectly

Behavior Details:

• No hard shifts

• No slipping

• No missing gears

• No abnormal behavior once warm

• Issue only appears when the car is cold

Observations (important):

• Transmission fluid temp ~23°C at startup when the issue appears

• Warning disappears around ~35–40°C

• No consistent drivability issues beyond the cold start condition





Fault Codes (from iCarsoft 3.0):

P174D00 Passive/Sporadic: Shift valve for 4th/6th gear in gear train half 2 - electrical fault

I also got (before exchanging the battery):

→ 0603 Passive/Sporadic: Load switch-off ( eEM)


Service History Notes:

• No known PDK fluid or filter service in ~12+ years

• I understand this is overdue, but unclear if it directly explains this behavior

Other Notes:

• Using an iCarsoft 3.0 scanner (limited diagnostics vs PIWIS)

• Not fully sure if battery registration/adaptation was properly completed

My Concern:

Given how the car behaves:

• Perfect once warm

• No shifting issues at all

• No progressive worsening

I want to avoid unnecessary mechatronics or transmission work unless there is clear evidence pointing there.


Questions:

1. Has anyone experienced this specific “no reverse when cold” behavior on the Macan PDK?

2. Could this realistically be related to battery condition/replacement or system reset/adaptation?

3. Does this pattern point more toward hydraulic pressure/fluid condition when cold?

4. Would a PDK fluid + filter service be the correct first step before considering anything invasive?

5. Based on the fault codes above, would you suspect electrical/control vs mechanical/mechatronic?

6. Any way to properly confirm battery registration/adaptation without PIWIS?


I’m trying to approach this logically and avoid jumping into invasive work without exhausting the basics first.

Any insight would be greatly appreciated.

Thank you.

 

Either the shift solenoid valve is intermittently an open circuit, or more likely the "Circuit Board" (which connects the solenoid to the Transmission Computer (TCU)) has an intermittent open circuit.
The Mechatronic can be pulled out of the bottom of the transmission, and the two black plastic Circuit Boards can be easily replaced. The shift valve solenoid can then also be easily replaced.

 

I would start by doing a PDK fluid change and recalibration. If that doesn't fix the issue then move on to the circuit boards and solenoids that VAGfan wrote about.

 

I would replace the two circuit boards, and then replace the fluid and both filters.
The DTC trouble code is pretty definitive as to what the problem is. The circuit board failing with an open circuit is pretty common on older Macans. The solenoid valves usually dont fail as an open circuit.

Replacement Circuit Board Porsche kit:
9A7-398-009-00 - Repair Set Delaware Porsche Parts

or a complete kit, including fluid, gaskets, and filters:
Audi B8/B8.5 S4 Quattro 3.0T Drivetrain DSG Transmission - 0b5398009fKT - DL501 Ultimate Mechatronic Rebuild Kit

And you will need this bolt kit for the subframe, as these are one-time-use bolts:
Audi B8/B8.5 S4 Quattro 3.0T Audi B8/B8.5 S4 Quattro 3.0T Search SiteSearch stretch bolt sunframe - 034-603-Z006 - X-Brace Stretch Bolt Subframe Hardware Kit