U2105 on 2003-2011 Saab 9-3 (Linear, Arc, Vector, Aero) — CAN Bus — No Communication With ECM/ECU (Manufacturer-Specific)
1 vehicles · 1 makes
Most Reported On
U2105 is an OBD-II diagnostic trouble code meaning “CAN Bus — No Communication With ECM/ECU (Manufacturer-Specific).” U2105 is a manufacturer-specific CAN bus code that generally means a module reported no communication with the engine control module (ECM/ECU) over the network. When the ECM cannot be reached, engine-related coordination breaks down, which can cause drivability problems, no-start conditions, or multiple warning lights. Because it can affect the engine controller, it should be addressed promptly. This code is most commonly reported on 2003-2011 Saab 9-3 (Linear, Arc, Vector, Aero).
Common Causes
Diagnostic Tools
To diagnose U2105, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
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- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
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- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
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- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
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- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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FAQ
What does U2105 mean?
U2105 stands for "CAN Bus — No Communication With ECM/ECU (Manufacturer-Specific)." U2105 is a manufacturer-specific CAN bus code that generally means a module reported no communication with the engine control module (ECM/ECU) over the network. When the ECM cannot be reached, engine-related coordination breaks down, which can cause drivability problems, no-start conditions, or multiple warning lights. Because it can affect the engine controller, it should be addressed promptly.
What are the most common causes of U2105?
The most common causes of U2105 are: ECM not powered (blown fuse, failed relay), Damaged or open CAN bus wiring to the ECM, Faulty engine control module, Loose or corroded ECM connector, Poor ground or high-resistance ground, Low or unstable battery voltage, Module configuration / programming error. The specific cause varies by vehicle.
How much does it cost to fix U2105?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by U2105?
Au7o has documented U2105 across 1 vehicle models from 1 manufacturers: Saab.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.