What Does C1148 Mean?
This code indicates the ABS control module has detected a coherency fault with the right front wheel speed sensor signal. A coherency fault means the RF wheel speed reading is significantly different from what the module expects based on the other wheel speed sensors. The RF wheel may appear to be spinning much faster or slower than the other wheels during normal driving, indicating a sensor or tone ring issue rather than actual wheel speed difference.
Safety Warning
ABS may activate unexpectedly or be disabled entirely due to inaccurate wheel speed data. Traction control may also behave erratically. Repair promptly.
Common Causes
30%
Incorrect tone ring installed with wrong tooth count from a previous repair, or aftermarket hub assembly with non-OE tone ring
25%
Damaged tone ring with multiple missing or damaged teeth causing erratic speed calculations
20%
Wrong tire size on the right front wheel compared to other wheels, causing a legitimate speed difference that exceeds module tolerance
15%
Intermittent sensor or wiring fault causing signal dropouts that corrupt the speed calculation
10%
Excessive wheel bearing play causing variable air gap and inconsistent signal amplitude
Diagnostic Steps
1
Step 1: Compare all four tire sizes and confirm they match. Even small differences (e.g., different brand with different rolling diameter) can trigger coherency faults. Check tire pressures as well.
2
Step 2: Monitor live data for all four wheel speed sensors while driving at a steady 30 mph. All four should read within 1-2 mph of each other on a straight road. Note which sensor deviates.
3
Step 3: Inspect the RF tone ring tooth count and compare to the specification and to the other wheels. Verify the correct part number hub assembly or tone ring is installed.
4
Step 4: Check the RF sensor waveform with an oscilloscope for signal dropouts, amplitude variations, or irregular patterns during wheel rotation.
5
Step 5: Address the root cause (replace tone ring, match tires, repair wiring), clear codes, and road test verifying all four wheel speeds track consistently.
Estimated Repair Cost
$80 - $500
Parts + labor, varies by vehicle and location
This code indicates the ABS control module has detected a coherency fault with the right front wheel speed sensor signal. A coherency fault means the RF wheel speed reading is significantly different from what the module expects based on the other wheel speed sensors. The RF wheel may appear to be s...
The most common cause of C1148 (Speed Wheel Sensor RF Coherency Fault) is: Incorrect tone ring installed with wrong tooth count from a previous repair, or aftermarket hub assembly with non-OE tone ring
Typical repair costs for C1148 range from $80 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS may activate unexpectedly or be disabled entirely due to inaccurate wheel speed data. Traction control may also behave erratically. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1148 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Chassis
System
Anti-lock Brake System (ABS) / Traction Control System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
