Ford C1175 Code: LR / Rear Wheel Speed Sensor Input Circuit Failure
Electrical fault in the left rear sensor circuit, or in the single rear-axle sensor on some Ford trucks.
Unverified: this manufacturer-specific definition comes from a single source or varies by model. Confirm it with a brand-specific scan tool.
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
- LR / Rear Wheel Speed Sensor Input Circuit Failure
- System
- Brakes, ABS & Chassis · Chassis
- Safe to drive?
- With caution
- Typical repair cost
- $0–$1,000
- DIY difficulty
- Moderate
C1175 means the ABS module found the left rear wheel speed sensor circuit open or shorted, but what 'left rear' refers to depends on the vehicle, which is why this page is marked as model-dependent. On four-sensor Fords such as the Escape, Focus, Fusion and Explorer it is simply the driver-side rear wheel. On many Ford trucks and vans with three-channel ABS, including Super Duty, E-Series and some F-150 and Ranger generations, there is only one rear sensor, mounted in the differential housing and reading an exciter ring on the differential carrier, and faults in that sensor are logged as C1175. On those trucks the checks are different: the sensor is under the axle, its magnetic tip collects wear metal from the gears, and a cracked or loose exciter ring inside the differential can only be fixed by opening the axle.
Can I keep driving? The brakes work normally, but ABS and traction control are off, so the rear can lock and slide under hard braking, especially when the bed or van is empty. Drive carefully, avoid heavy towing in bad weather, and get it repaired soon.
How to read C1175
- C Chassis
- 1 Manufacturer-specific
- 1 Brakes, ABS & Chassis
- 75 Specific fault
Symptoms
- ABS light on, sometimes with the red brake warning light on trucks with rear anti-lock
- Rear wheels lock up easily under hard braking with an empty bed
- Speedometer erratic or dead on trucks where the rear sensor also supplies vehicle speed
- Code appeared after differential service, gear change or axle work
- Gear oil wetness around the sensor on the differential housing
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Rear sensor failed or its tip coated in wear metal from the differential (single-sensor trucks)
- Lead damaged along the axle housing or frame rail, or connector corroded (driver-side on four-sensor vehicles)
- Left rear sensor on four-sensor cars cracked or shorted by rust in its bore
- Exciter ring on the differential carrier cracked, loose or damaged, or wrong ring after a gear change
- Leaking sensor O-ring letting gear oil into the connector
- ABS module input fault
Diagnosis step by step
Find out which rear layout you have
Look at the rear axle: a single sensor bolted into the top or front of the differential housing means a three-channel system, while a sensor at each rear wheel means C1175 is the left rear. The rest of the test depends on this.
Tools: Flashlight
Measure the sensor from the connector
Unplug the rear sensor connector and measure across the sensor side. Passive differential sensors typically read in the one to a few thousand ohm range; an open or a reading near zero condemns the sensor.
Tools: Multimeter
Pull and inspect the sensor tip
Remove the single hold-down bolt and lift the sensor out of the housing. A fuzzy coat of metal on the magnetic tip, a cracked body or a hardened O-ring are all reasons to clean or replace it.
Tools: Screwdriver, Flashlight, Towels & shallow pan
Check the output while turning the wheels
With the rear raised and the transmission in neutral, turn a rear wheel by hand and measure AC voltage at the sensor. The voltage should rise as you turn faster; no output with a good sensor points to the exciter ring.
Tools: Multimeter
Trace the harness to the ABS module
Follow the lead along the axle and frame to the ABS module and check for chafe at the axle vent, spring or frame clips. Test each wire for continuity end to end and for shorts to ground.
Tools: Multimeter, Flashlight
Refit, top up and verify
Install the sensor with a new O-ring and torque the bolt to spec, then top up the differential oil if any was lost. Clear the codes and road test above about 20 mph.
Tools: Torque wrench, OBD-II scanner
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 sensor tip and fit new O-ring | Yes | $0–$80 |
| Replace rear axle or left rear wheel speed sensor | Yes | $90–$300 |
| Repair rear sensor harness | No | $100–$300 |
| Replace differential exciter ring (axle teardown) | No | $400–$1,000 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Depends
C1175 doesn't affect the emissions part of a US smog check. In states with a safety inspection, the ABS light can cause a failure.
Frequently asked questions
My truck has no sensor at the left rear wheel. Why does it say left rear?
On many Ford trucks and vans with a single rear sensor in the differential, that sensor's faults are reported as C1175. The name comes from the four-sensor code list, but the part to check is the differential sensor.
Is metal on the sensor tip normal?
A little fine paste is normal because the tip is a magnet sitting in gear oil. A heavy furry coating weakens the signal, and large chunks point to worn or damaged differential parts.
Why did C1175 appear after a gear swap?
The exciter ring sits on the differential carrier. If it was damaged, left off or the wrong tooth count was fitted, the sensor can't read it correctly, and the speedometer is often wrong too.
Can I clean the sensor instead of replacing it?
Often, yes. If it measures within range and the body isn't cracked, wiping the metal off the tip and fitting a new O-ring may cure it.
Sources
- Manufacturer public service information (cross-checked)
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