A 2012 Audi A6 arrived with an engine that fired and immediately stalled, dropping a gearbox error on the dash and a P157000 code in the background. On the second start attempt, the instrument cluster read that the key was not in range. The technician placed the key in the emergency designated spot, and the vehicle started without a problem.
Parsing the mixed codes
I see our diagnostic platform process countless mixed code combinations, but this specific sequence is a classic misdirection. The scanner pulled P157000, P200600, P200400, P170100, and U111300. It is easy to look at a transmission lock code like P170100 alongside an engine control module lock code like P157000 and suspect a major module failure. But the vehicle behavior points directly to the drive authorization system. When the key was placed in the inductive zone, the passive RFID transponder bypassed the wireless communication and allowed the start.
The comfort module bulletin
The diagnostic engine matched these exact symptoms to a known software issue in the J393 comfort module. According to TSB 2030580, the remote key can sporadically send incomplete immobilizer data to the J393 unit. This interrupts the drive authorization process to both the ECM (J623) and the TCM (J217). The modules log a locked status, the dashboard throws a fake transmission warning, and the engine cuts out. The repair involves updating the J393 module via SVM code 46A004 or 46A013 to version 0433 or newer. Testing the CR2032 key battery with a multimeter is the sensible first diagnostic step to rule out a simple voltage drop.
The unrelated intake fault
The remaining codes, P2004 and P2006, represent a completely separate mechanical issue on the 3.0 TDI engine. P2004 indicates the Bank 1 swirl flaps are stuck open, while P2006 flags them as stuck closed. This contradiction happens when the plastic linkage connecting the servo motor to the flap axis wears out or detaches. The servo travels beyond its programmed stops, confusing the engine computer. Testing requires a visual inspection of the Bank 1 linkage and checking the ball joints for play by hand. Alternatively, heavy carbon buildup from the EGR system can jam the flap axis itself.
Next steps
Reviewing multiple codes together prevents technicians from chasing ghost transmission faults. Have you seen this J393 immobilizer behavior on other 4G chassis vehicles?