U2113

Code

OPEL U — Network/User

CAN-Bus No Communication with SDM (Airbag)

Brand: OPEL

Type: U — Network/User

Views: UK: 3 EN: 10 RU: 6

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Page language: EN

Causes

Open/short in CAN-H or CAN-L wiring between SDM and main CAN trunk
Faulty SDM (airbag module) or internal SDM power/ground failure
Corroded/damaged connectors at SDM or junctions
Missing or incorrect CAN termination (open or shorted termination resistor)
Low battery voltage, poor battery/ground connections, or intermittent power supply
Software/configuration mismatch after module replacement or programming error

Symptoms

SRS / airbag warning lamp illuminated or flashing on instrument panel
Possible disabling of airbag and seatbelt pretensioners (SRS not ready)
Stored U2113 and possibly other CAN communication DTCs in scan tool
No SRS data/messages available on diagnostic tool from the SDM
Intermittent faults or faults reappearing after clearing codes

What to check

Connect a capable scan tool; read all U-codes and freeze frame data; note date/time of occurrence
Verify vehicle battery voltage and charging system; ensure battery >=12.2 V at rest and stable during cranking
Visually inspect SDM connectors and harness for corrosion, water damage, bent pins, or chafing
Check for related communication codes from other modules (network-wide issues)
Measure CAN bus voltages at a known good point and at the SDM connector (see signal parameters)
Measure CAN bus termination resistance (approx. 60 ohms across CAN_H to CAN_L with power off)

Signal parameters

Idle (recessive) voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (to chassis ground) — actual values vary by vehicle
Dominant state voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
Typical differential voltage (dominant) ≈ 2.0 V
Nominal bus termination resistance ≈ 60 ohms (two 120 ohm resistors in parallel)
Common CAN data rates found on vehicles: 125 kbps, 250 kbps, 500 kbps (verify OEM bus speed before testing)

Diagnostic algorithm

Safety first: follow manufacturer SRS safety procedures. Disable battery and follow the OEM wait/time requirements before disconnecting SDM connectors or handling airbag components.
Retrieve all DTCs and freeze-frame information with a factory-capable scan tool. Note whether U2113 is permanent, current, or historical and whether other modules report network faults.
Check battery voltage and ground integrity. Repair any low-voltage or poor-ground issues; re-test for communication.
Perform a visual inspection of the SDM connector, nearby harness, and body harness routing for damage, corrosion, or water entry. Repair any obvious issues.
With ignition on (and following safety procedures), measure CAN_H and CAN_L at the SDM connector and at other accessible nodes. Compare values to expected idle/dominant levels.
Check bus termination resistance with power off; expect ~60 ohms across CAN_H and CAN_L. If open or shorted, trace wiring for breaks or shorts to chassis or battery.
Use an oscilloscope or CAN bus analyzer to view waveform quality and message traffic. Confirm whether the SDM is transmitting; if no messages, the SDM may be not powered or faulty.
Isolate the fault by disconnecting non-essential nodes or branches (one at a time) and observe if communication is restored. This can locate a module or wiring branch dragging the bus down.
If wiring and bus integrity check good, follow OEM procedures to test or replace the SDM. Reprogram/configure the replacement SDM as required by manufacturer.
Clear codes, cycle ignition, and verify restoration of communication and that no new SRS faults appear. Perform full system scan and SRS self-tests as specified by OEM.
If intermittent or unresolved, consult factory service literature for module-specific diagnostics or escalate to dealer-level tools/diagnostics.

Likely causes

Damaged/loose connector or corroded pins at the SDM
Open or shorted CAN wiring in the harness near the SDM (common failure area)
Failed SDM (most likely when wiring checks OK)
Poor battery/ground causing intermittent module startup and loss of communication
Aftermarket device or recently replaced module not programmed or configured correctly

Fault status

⚠️ Status

No communication with SDM (airbag). SDM not responding on CAN bus; SRS system disabled or reporting fault.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1-4 hours

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