C1A00 on Ford: How to Diagnose & Fix
Stability Control System Fault
1 Ford model · 1 documented issue · 1 critical · $900-$2,500 repair
C1A00 on Ford by model: symptoms, diagnosis and fix
The 2012 Mk3 Focus was the first Focus with a fully electric rack-mounted power steering assist (EPAS). The torque/position sensor and motor assembly inside the rack, and the power steering control module (PSCM) integrated with it, fail intermittently - often heat-soaked on long drives or hot days. The dash shows "Power Steering Assist Fault - Service Now", the wheel goes heavy with no warning, and steering no longer self-centers. Failures are frequently intermittent at first (assist returns after a key cycle) and then become permanent. Because the assist motor is integral to the rack, Ford's repair is a complete steering gear replacement. Unlike the Fusion/Taurus/Flex family, which got NHTSA recall 15V340 for the same motor-sensor defect, the Focus was never recalled despite hundreds of NHTSA complaints, and was instead the subject of a class-action suit covering 2012-2014 Focus and Focus Electric.
Common Symptoms
- Power Steering Assist Fault - Service Now message
- Steering suddenly becomes very heavy while driving
- Assist comes back after restarting the car
- Steering does not return to center after a turn
- Fault appears more often on hot days or after long drives
How to Fix
Scan the PSCM for stored codes first (low battery voltage and corroded connectors at the rack can mimic the fault). If EPAS-internal codes are present, Ford's only repair is replacement of the complete electric steering gear assembly and PSCM software programming; some cars are fixed by a PSCM reflash alone when no hard codes are stored. Verify battery and alternator output before condemning the rack, since low system voltage will drop assist and set the same message.
Sources for this issue (5)
- Power steering assist fault | Focus Fanatics Forumforum
- Sudden and complete steering failure | Focus Fanatics Forumforum
- NHTSA Recall 15V340 - Ford, Failure of Electric Power Steering Assist (same motor sensor defect, Focus excluded)article
- Ford Steering Problems Come into Focus - Safety Research & Strategiesarticle
- 2012 Ford Focus Power Steering Failure: 122 Complaints - CarComplaintsarticle
C1A00 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 C1A00 mean on a Ford?
C1A00 stands for "Stability Control System Fault." This is a chassis/stability-control code that signals a general fault within the electronic stability control system — the network of sensors and the controller that keep the vehicle from skidding or losing traction during hard cornering or slippery conditions. C1A00 typically means the stability control module detected an internal fault or a problem somewhere in the system it can't fully resolve, so it may disable stability and traction control and turn on the related warning lights. Importantly, C1A00 is a manufacturer-specific code and its precise meaning varies by brand, and the full code often includes additional sub-numbers needed to pinpoint the exact fault. Because it's broad, an accurate diagnosis usually requires a capable scan tool to read the extended code and any companion codes. On Ford it is documented across 1 model: Focus.
What are the most common causes of C1A00?
The most common causes of C1A00 are: Internal stability control module fault, Companion sensor faults (wheel speed, steering angle, yaw/lateral) triggering the system, Wiring, connector or ground problems in the stability control circuit, Low system or battery voltage / charging issue, Module software, calibration or configuration fault, Damaged or unplugged sensor harness after service, Faulty ABS/stability hydraulic control unit (less common). The specific cause varies by vehicle.
How much does it cost to fix C1A00 on a Ford?
Published repair estimates on Ford range from $900 to $2,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for C1A00 on a different make?
View C1A00 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.