U2105 on 2003-2011 Saab 9-3 (Linear, Arc, Vector, Aero) — CAN Bus — No Communication With ECM/ECU (Manufacturer-Specific)
1 vehicles · 1 makes
How to diagnose and fix U2105: most-reported vehicles
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Saab 9-3 · 2003–2011
Second-gen 9-3 (2003-2011) sunroof drains clog with debris (pollen, leaves). Water then overflows into the headliner, runs down the A-pillars, soaks the carpet, and pools in the front footwell — directly under the DICE (Driver Information Central Electronics) and TWICE modules. Wet modules can short and cause a cascade of weird electrical faults (no-start, dead instrument cluster, ABS faults, etc.).
Common Symptoms
- wet carpet
- no-start intermittent
- dead dash
- multiple electrical warnings
- mildew smell
How to Fix
Clear sunroof drains annually (compressed air from above, fishline gently from below). If carpet is wet, dry IMMEDIATELY — remove driver carpet and inspect the modules. Once a module is corroded the only fix is replacement and recoding ($300-$1,200). Aftermarket dehumidifier packs in footwell help in humid climates.
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U2105 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
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.