Ford C1145 Code: RF Wheel Speed Sensor Input Circuit Failure
Ford's ABS module found an open or short in the right front (passenger-side) wheel speed sensor circuit.
Safety first · Consult a professional
- Braking system affected: ABS may be disabled. Drive carefully and have it checked promptly.
At a glance
Severity: Moderate
- Meaning
- RF Wheel Speed Sensor Input Circuit Failure
- System
- Brakes, ABS & Chassis · Chassis
- Safe to drive?
- With caution
- Typical repair cost
- $0–$1,400
- DIY difficulty
- Moderate
C1145 is Ford's electrical fault code for the right front wheel speed sensor. When the ignition is switched on, the ABS module sends a small supply or test current through each sensor loop and checks that it returns within limits; C1145 means the RF loop is open, shorted to ground or shorted to voltage. Because this is a circuit check, the code can set before the vehicle even moves, which separates it from C1234, the RF 'signal missing' code that needs driving to detect. Ford, Lincoln, Mercury and Ford-based Mazda models use this numbering in place of the generic C0040. The problem is usually the sensor's internal coil or electronics, its pigtail, or one of the two wires between the sensor and the ABS module.
Can I keep driving? Brakes still work normally, but ABS, traction control and AdvanceTrac are disabled, so the front wheels can lock in an emergency stop. Drive gently, leave extra room on wet or icy roads, and repair it soon.
How to read C1145
- C Chassis
- 1 Manufacturer-specific
- 1 Brakes, ABS & Chassis
- 45 Specific fault
Symptoms
- ABS light on as soon as the engine starts, often with the traction control light
- AdvanceTrac or RSC warning on SUVs and trucks equipped with stability control
- Code returns immediately after clearing, even without driving
- Speedometer or cruise control affected on some trucks where the ABS module supplies vehicle speed
- No brake pedal pulsing or noises; the ABS simply stays off
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Right front wheel speed sensor failed internally (open coil or dead active sensor)
- Sensor pigtail cut, crushed or pulled apart at the knuckle, often after brake, ball joint or hub work
- Corroded or water-filled connector where the sensor lead joins the body harness in the wheel well
- Wire shorted to ground or to another circuit where the harness passes the frame or inner fender
- ABS module input or connector pin fault (suspect when both front sensors report circuit codes)
Diagnosis step by step
Confirm the code and when it sets
Clear the ABS codes, switch the ignition off and on, and read again without moving. If C1145 returns at key-on, you're dealing with an electrical fault, not a gap or tone ring problem.
Tools: OBD-II scanner
Swap the front sensors to see if the fault follows
On many Ford trucks the left and right front sensors are the same part. Swap them, clear the code and cycle the key; if the code changes to C1155, the sensor is bad, and if it stays C1145, the problem is in the wiring or module.
Tools: Screwdriver, OBD-II scanner
Check the sensor itself
Older passive sensors can be measured across their two pins and should read in the same range as the left front sensor, typically around one to a few thousand ohms. Active sensors can't be judged by resistance; check them by substitution or with the module's supply present.
Tools: Multimeter
Test both wires to the module
With the battery disconnected and the ABS connector unplugged, check continuity of each wire from the sensor connector to the module connector (a few ohms at most) and check each for continuity to ground (should be none).
Tools: Multimeter
Check for a short to voltage
Reconnect the battery, leave the ABS connector unplugged, turn the key on and measure each sensor wire to ground. Any voltage means the harness is touching a powered circuit somewhere along the route.
Tools: Multimeter
Repair, clear and self-test
Repair or replace the faulty part, reconnect everything, clear the codes and cycle the ignition. Finish with a short drive above about 20 mph to confirm C1234 doesn't appear in its place.
Tools: OBD-II scanner, Torque wrench
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean and reseal wheel-well connector | Yes | $0–$90 |
| Replace right front wheel speed sensor | Yes | $90–$300 |
| Repair or replace sensor harness section | No | $100–$300 |
| Replace front hub assembly with integrated sensor (where fitted) | No | $280–$700 |
| ABS module rebuild or replacement | No | $300–$1,400 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Depends
C1145 doesn't affect the emissions part of a US smog check. In states with a safety inspection, the illuminated ABS light can cause a failure.
Frequently asked questions
What's the difference between C1145 and C1234?
C1145 is an electrical fault in the right front sensor circuit, detected by the key-on self-test. C1234 means the circuit looks electrically fine but the sensor produces no usable signal while driving, which points to gap, tone ring or bearing problems.
I have C1145 and C1155 together. Are both sensors bad?
Two front sensors rarely fail at the same moment. Look for a shared cause: a damaged harness section where both leads run together, a corroded ABS module connector or an ABS module fault.
Is 'RF' the passenger side?
Yes. Codes are named from the driver's seat, so on US vehicles right front is the passenger-side front wheel.
Why doesn't my basic code reader show C1145?
C-codes are stored in the ABS module, and many cheap readers only talk to the engine computer. You need a scan tool with ABS access to read and clear it.
Sources
- Manufacturer public service information (cross-checked)
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