U02AC

Code

Generic U — Network/User

Lost Communication With Turbocharger/Supercharger Boost Control A

Brand: Generic

Type: U — Network/User

Views: UK: 21 EN: 26 RU: 15

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Page language: EN

Faulty Turbocharger/Supercharger Boost Control A module (no response)
Open, shorted, or intermittent wiring between boost control module and vehicle network (CAN/LIN)
Poor power or ground to the boost control module
Network termination or bus fault (missing resistor, short to battery or ground)
Connector corrosion, bent pins, or water intrusion at module or junctions
Module not configured or programmed correctly after replacement or update

Check for additional U- or P-codes that indicate network or module faults
Verify battery voltage and charging system health (stable 12–14.5 V with engine running)
Visually inspect connectors and wiring at the boost control module and related junctions for corrosion, damage, or loose pins
Use a scan tool to request module presence and view live data/message counters
Check CAN/LIN bus idle voltages with a multimeter (CAN recessive ~2.5 V on CAN_H and CAN_L; dominant states differ) and waveform with an oscilloscope or CAN analyzer
Measure resistance between CAN_H and CAN_L at key points to check termination (~60 ohms total for two 120 ohm terminators on CAN)

Typical CAN bus idle: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive). Dominant: CAN_H rises ≈ 3.5 V, CAN_L falls ≈ 1.5 V
Node-to-node termination: ~60 ohms measured across CAN_H and CAN_L at two-terminator systems
Message presence: boost control module should transmit periodic messages at a defined rate (use CAN tool to view ID and frequency)
LIN bus idle: ~battery voltage when idle; active frames follow LIN timing protocol (if boost actuator uses LIN)
Absence of periodic frames or long gaps between frames indicates lost communication

Retrieve freeze frame and stored codes; note any other network-related U-codes.
Attempt a module presence check with a capable scan tool. If module is shown as 'not present', proceed with network checks.
Visually inspect harnesses/connectors at the boost control module and at any intermediate junction boxes. Repair any physical damage or corrosion.
Verify module supply and ground: with key on (or engine running if required), measure reference power and ground at the module connector. Repair open circuits, blown fuses, or faulty relays.
Check bus health: measure CAN_H and CAN_L voltages with key on. If voltages are abnormal, isolate sections of the bus to find short or open. Use an oscilloscope/CAN analyzer to confirm valid waveform and message traffic.
If the bus is healthy, check resistance between CAN_H and CAN_L at the module connector (expect ~60 ohms total). If not, inspect termination resistors at bus ends.