I too had P026A code and a car that went into limp mode (2014 Passat TDI SEL Premium, 75K). I flushed the air cooler and replaced the MAP sensor per flyboybob's instructions. Worked like a champ. Code cleared, car ran better than it has in a while. But two days later, on freeway driving, car went into limp mode with no lights. A minute or so later, got the flashing glow plug and a check engine light. Limped the 15 miles home and here are the codes. I called the dealer where I purchased it. TDI warranty expires on 3/16/24. Local dealer is CRAP, so I had it towed the 70 miles back to them after discussion with the service manager.
Car Scanner ELM OBD2
Version: 1.104.0/1.104.0/iOS
DTC report
Connection profile: Volkswagen OBD-II / EOBD Diesel DPF var.1Date: 2/26/2024 6:20:34 AM
VIN: 1VWCN7A3XEC052142
============================
OBD-IIOBD-II
DTCs: 2
----------------------------
P0237 [0x0237]
Turbocharger (TC) boost pressure sensor/supercharger (SC) boost pressure sensor A - low input
TC Boost Sensor Circuit Low Voltage
Status: Confirmed
----------------------------
P0111 [0x0111] Archive (inactive)
Intake air temperature (IAT) sensor - range/performance problem
Intake Air Temperature (IAT) Sensor Performance
Status: Permanent
============================
19. CAN Gateway
No DTC found.
============================
02. Transmission control unit
No DTC found.
============================
03. ABS control unit
No DTC found.
============================
01. Engine control unit01. Engine control unit
DTCs: 1
----------------------------
05170 [0x001432]
P023700: Turbocharger Boost Sensor (A) Circ., Low Input
Status: Test failed, Test failed (current drive cycle), Pending, Confirmed, Test failed since last DTC clear, Warning indicator requested