C1103: ABS/Brake System Circuit Fault (manufacturer-specific)
2 vehicles · 2 makes · $200-$2,000 repair
Most Reported On
C1103 is an OBD-II diagnostic trouble code meaning “ABS/Brake System Circuit Fault (manufacturer-specific).” This is a chassis code set by the ABS/brake control module, and its precise meaning is manufacturer-specific. On many vehicles it refers to a fault in an ABS-related circuit such as the hydraulic brake switch or a wheel-speed/control circuit, while some makes (for example certain Mercedes-Benz) assign it to a specific axle circuit. In general it indicates the ABS module found an electrical problem in a brake-system input or control circuit, which can disable anti-lock braking and stability features. Because braking-related faults affect safety, it should be diagnosed against the correct service information for the specific make. This code is most commonly reported on 2011-2025 Audi A8 (L, Premium, Prestige), and 2002-2012 Nissan Altima, with repair costs ranging from $200 to $2,000.
Common Causes
Typical Repair Cost
Based on 2 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose C1103, 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+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- 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)
- Repair Reports with verified fixes
- 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
- Live data stream & graphing
- 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)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
FAQ
What does C1103 mean?
C1103 stands for "ABS/Brake System Circuit Fault (manufacturer-specific)." This is a chassis code set by the ABS/brake control module, and its precise meaning is manufacturer-specific. On many vehicles it refers to a fault in an ABS-related circuit such as the hydraulic brake switch or a wheel-speed/control circuit, while some makes (for example certain Mercedes-Benz) assign it to a specific axle circuit. In general it indicates the ABS module found an electrical problem in a brake-system input or control circuit, which can disable anti-lock braking and stability features. Because braking-related faults affect safety, it should be diagnosed against the correct service information for the specific make.
What are the most common causes of C1103?
The most common causes of C1103 are: Faulty hydraulic brake/pressure switch (on applicable makes), Wheel-speed sensor or related circuit fault, Damaged, corroded, or open wiring/connectors, Poor grounds or low supply voltage to ABS module, Internal ABS/EBCM module failure, Manufacturer-specific axle/sensor circuit fault. The specific cause varies by vehicle.
How much does it cost to fix C1103?
Repair costs for C1103 range from $200 to $2,000, depending on the vehicle and root cause.
Which vehicles are affected by C1103?
Au7o has documented C1103 across 2 vehicle models from 2 manufacturers: Audi, Nissan.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.