C1AA6 on Toyota: How to Diagnose & Fix
Manufacturer-Specific EPS/Steering Control Circuit Fault
1 Toyota model · 1 documented issue
C1AA6 on Toyota by model: symptoms, diagnosis and fix
Owners have reported Toyota Safety Sense warnings, unavailable adaptive cruise, and intermittent pre-collision or lane-keeping alerts when the radar or camera becomes obstructed by weather, road film, or dust. While some level of sensor blockage is expected, complaints indicate the system can become unavailable sooner than expected in real-world conditions, especially on dirty winter roads or off-pavement use. The result is nuisance warnings and loss of driver-assist features until the sensors clear.
Common Symptoms
- Pre-Collision System unavailable message
- Adaptive cruise control disabled
- Lane tracing assist unavailable
- Radar sensor blocked warning
- Intermittent driver-assist shutdown in bad weather
How to Fix
Inspect and clean the front emblem/radar area and windshield camera zone, then check for alignment issues if warnings persist in clear conditions. Dealers can verify radar/camera calibration and inspect for software updates or mounting problems after minor impacts or windshield replacement. If the issue only occurs in severe weather, cleaning and preventive protection are usually the main remedies.
Owner tips & cautions
- TipOwners in winter climates recommend keeping a microfiber towel in the vehicle to wipe the front emblem and camera area during fuel stops.
Sources for this issue (1)
C1AA6 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 C1AA6 mean on a Toyota?
C1AA6 stands for "Manufacturer-Specific EPS/Steering Control Circuit Fault." C1AA6 is an obscure manufacturer-specific chassis trouble code, generally within the Electric Power Steering or steering-control code family. It indicates the steering control module detected an electrical or signal fault it considers out of specification. The exact definition is set by the vehicle manufacturer and could not be confirmed against a public standard, so it should be read at the system level: a steering-system sensor, motor, or wiring problem. Symptoms commonly include reduced or inconsistent power steering assist and a steering or warning light. On Toyota it is documented across 1 model: Land Cruiser.
What are the most common causes of C1AA6?
The most common causes of C1AA6 are: Wiring or connector fault in the steering control circuit, Faulty steering sensor (angle or torque), EPS motor or control module internal fault, Low or unstable supply voltage, Poor ground or corroded connector, Module software/calibration fault. The specific cause varies by vehicle.
How much does it cost to fix C1AA6 on a Toyota?
Repair costs vary widely with the root cause and Toyota model; each issue on this page carries its own estimate where one is published.
Looking for C1AA6 on a different make?
View C1AA6 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.