Audi S5 B9 Engine Swap Limp Mode (CWGD to CWD) - P0642 U060B

Hi everyone,

I’ve just completed an engine swap on my 2017 Audi S5 (B9). The original CWGD engine seized, and I’ve replaced it with a CWD unit. I am currently using the CWD wiring harness that came with the new engine.

The car is stuck in permanent Limp Mode with the following persistent codes:

• P0642 00 - Sensor Reference Voltage A: Voltage too Low

• U0609 00 - Sensor 1 for Intake Manifold Pressure: No Communication

• U060B 00 - Sensor 1 for Boost Pressure: No Communication

• P2279 00 - Leak in Air Intake System

What I’ve found so far:

1. Fuses: Found missing fuses in Footwell Row A (slots 1 & 2) and replaced them. This brought the Charge Air Pressure sensor back to life (~31 kPa at idle).

2. Sensor Mismatch: Intake Manifold Pressure Sensor 2 is still reading 0 kPa and shows as "Not Installed" on my diagnostics.

3. Basic Settings: I’ve successfully run the Throttle Valve Adaptation. However, the Turbocharger Test (IDE00457) fails with "Conditions not correct," likely because of the active U060B code.

4. Voltage: Terminal 30 voltage is hovering around 11.8V-11.9V.

The Question: Since I don't have the original CWGD harness, I suspect the CWD harness is pinned differently at the ECU for the second pressure sensor, causing the P0642 reference voltage drop and the "No Communication" errors.

Has anyone successfully mapped the CWD harness to a CWGD ECU, or do I need to bridge the signal wires for the two MAP sensors to satisfy the ECU's plausibility check?

Any advice on the pinout differences at the ECU between these two engines would be massive.