OBD2 Car ScannerWhat does C1091 mean?
C1091 stands for Speed Wheel Sensor All Coherency Failure. A chassis module has found a fault in a system like ABS, traction or stability control, steering or suspension.
Chassis codes cover the ABS, traction control, steering and suspension. When the car's computer sees a reading outside its normal range, it stores this code and may turn on a warning light on the dashboard.
Common causes
- Faulty or dirty wheel speed sensor
- Damaged sensor wiring
- Low brake fluid
- Faulty ABS pump or module
What to do
- Read all stored and pending codes with a scanner. Several codes together often point to one cause.
- Note the freeze frame data (speed, temperature, load) recorded when the code was set.
- Inspect the wiring and connectors of the part named in the code for damage, corrosion or looseness.
- Fix the most likely and cheapest cause first, then clear the code and drive to see if it comes back.
Read this code from your own car
Plug in a cheap ELM327 adapter and the app shows every fault code, what it means and how to fix it.
Frequently asked questions
What does C1091 mean?
C1091 means “Speed Wheel Sensor All Coherency Failure”. It belongs to the chassis system group: A chassis module has found a fault in a system like ABS, traction or stability control, steering or suspension.
Is it safe to drive with C1091?
Avoid driving long distances. This kind of fault can cause damage or affect safety, so get it checked as soon as possible.
How do I clear C1091?
Fix the cause, then clear the code with an OBD2 scanner or app. If the fault is still there, the code will come back.
Related codes
- C008ATCS Mode Control (Subfault)
- C0100Rear ABS (both wheels) solenoid/motor #1 circuit malfunction
- C0300Rear Propshaft Speed Sensor
- C1000Manufacturer Controlled DTC
- C1095ABS Hydraulic Pump Motor Circuit Failure
- C1096ABS Hydraulic Pump Motor Circuit Open
- C1097ABS Hydraulic Pump Motor Circuit Short To Ground
- C1098ABS Hydraulic Pump Motor Circuit Short To Battery
Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.