C1101: How to Diagnose & Fix — ABS System Battery/Charging Voltage High
2 vehicles · 2 makes
How to diagnose and fix C1101: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Hyundai Sonata · 2015–2017
The Motor-Driven Power Steering (MDPS) unit can fail, illuminating the EPS warning light and causing sudden loss of power assist or a steering wheel that becomes very tight/hard to turn - sometimes during low-speed maneuvers (parking, tight turns) and sometimes at highway speed (~35 mph). Owners report having to stop, shift to park, and restart the engine to clear the light, and that the wheel can briefly 'lock' or require very high effort. Root causes traced to the MDPS module/motor, wiring-harness connections, or the steering-angle sensor. Hyundai issued a warranty extension (TSB 23-ST-003H) covering the MDPS for reduced assist and/or MDPS warning-lamp illumination on certain 2015-2017 model-year Sonata and Sonata Hybrid/Plug-in vehicles from 5yr/60,000 mi to 15yr/150,000 mi.
Common Symptoms
- EPS / MDPS warning light on
- Sudden loss of power steering assist
- Steering wheel very hard to turn or briefly locked
- Loss of assist during tight low-speed turns or at ~35 mph
- Light clears only after restarting the engine
How to Fix
Scan for MDPS-related codes and inspect the wiring harness/connectors and steering-angle sensor before condemning the unit; repairing a connection sometimes resolves it. A failed MDPS module is replaced. For certain 2015-2017 vehicles the MDPS/EPS unit is covered under the extended warranty (15yr/150,000 mi) when the EPS light illuminates - have it documented and repaired under that coverage.
Sources for this issue (4)
Nissan Altima · 2007–2013
The ABS/VDC control unit stores a wheel speed sensor code (C1101-C1104). Nissan's bulletin lists sensor damage, a missing sensor signal, short circuits and bent, corroded or contaminated connector pins as the things to check. 2007-2013 Nissan vehicles equipped with ABS/VDC, which includes the 2007-2012 Altima.
How to Fix
Per Nissan bulletin NTB10-102a, the technician records the active codes, clears them and road-tests above 13 mph to confirm the code returns, then checks the suspect sensor for damage, its output with a wheel sensor tester, the harness for shorts and the connectors for bent pins or corrosion before replacing anything. Nissan says not to replace a sensor based on the code alone. Normal warranty rules apply; this is not a recall or a promise of free repair. A stored code alone does not establish a failed sensor. The sensor, harness or connector repair follows the diagnostic result; do not infer that driving with a brake warning is safe.
Sources for this issue (1)
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C1101 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 C1101 mean?
C1101 stands for "ABS System Battery/Charging Voltage High." This is a chassis (ABS/stability control) code indicating the anti-lock brake or electronic stability module detected battery/charging system voltage outside its acceptable range, typically too high. The ABS module monitors supply voltage because it needs stable power to operate the pump and solenoids safely; out-of-range voltage can make it disable ABS/traction features as a precaution. On most makes this points to a charging-system problem rather than a brake fault, though the exact wording can vary by manufacturer.
What are the most common causes of C1101?
The most common causes of C1101 are: Overcharging alternator / faulty voltage regulator, Weak, failing, or corroded battery, Loose or corroded battery terminals and ground straps, Poor connections at the ABS module power feed, Damaged charging-system wiring, Faulty ABS/EBCM module (less common). The specific cause varies by vehicle.
How much does it cost to fix C1101?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by C1101?
Au7o has documented C1101 across 2 vehicle models from 2 manufacturers: Hyundai, Nissan.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.