Ford C1155 Code: LF Wheel Speed Sensor Input Circuit Failure
Ford's ABS module saw the left front (driver-side) sensor circuit go open or shorted, often only now and then.
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
- LF Wheel Speed Sensor Input Circuit Failure
- System
- Brakes, ABS & Chassis · Chassis
- Safe to drive?
- With caution
- Typical repair cost
- $0–$300
- DIY difficulty
- Moderate
C1155 is Ford's code for an electrical fault in the left front wheel speed sensor circuit, the Ford equivalent of generic C0035. The ABS module monitors the current flowing through the sensor loop all the time and flags C1155 when that current drops to nothing (open circuit) or jumps out of range (short). On Explorers, F-150s, Rangers and other Fords, a large share of these faults are intermittent: a wire that has broken inside its insulation where the lead flexes between the steering knuckle and the body makes contact when the wheel points straight and loses it at full lock or over bumps. That's why C1155 often comes back hours or days after being cleared, and why a quick resistance check on the bench can look perfect even though the fault is real.
Can I keep driving? Braking is normal, but ABS and stability control drop out whenever the fault is active, so the driver-side front wheel can lock in a panic stop. Keep speeds sensible in bad weather and get the circuit repaired soon.
How to read C1155
- C Chassis
- 1 Manufacturer-specific
- 1 Brakes, ABS & Chassis
- 55 Specific fault
Symptoms
- ABS and traction lights that come on over rough roads or during tight turns
- Light stays off for days after clearing, then returns
- AdvanceTrac/RSC off message on stability-control SUVs
- Light sometimes goes out again after a restart
- Visible damage or tape on the driver-side sensor lead near the knuckle
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Wire fatigue break inside the sensor lead where it flexes with steering and suspension travel
- Left front sensor failing internally (often intermittently with heat)
- Green corrosion in the wheel-well connector that has wicked up into the wire
- Harness clip broken so the lead rubs on the tire, brake hose bracket or frame
- Loose or fretted terminal at the ABS module connector
- ABS module input fault
Diagnosis step by step
Check the history and occurrence count
Look at the ABS module's freeze data or occurrence counter if your scan tool shows it. A code that has set many times and cleared itself is the signature of a flexing wire or loose terminal rather than a dead sensor.
Tools: OBD-II scanner
Wiggle test with live data
With the front wheels raised and the ignition on, watch for new C1155 events or the sensor status PID while you flex the lead from the sensor to the connector, and turn the steering lock to lock. The spot where the fault appears is the spot to repair.
Tools: OBD-II scanner, Flashlight
Measure while flexing
Unplug the sensor at the body connector and measure the loop on the sensor side while bending the lead in several places. Any flicker to open or a jumping value confirms an internal wire break.
Tools: Multimeter
Open the wheel-well connector
Pull the liner back if needed and separate the connector. Green or white crust on the terminals, or wire that is dark under its insulation, means the section needs replacing rather than cleaning.
Tools: Screwdriver, Flashlight
Check terminal tension at the ABS module
With the ABS connector unplugged, gently insert a matching test terminal into the two sensor cavities. A loose feel means the terminal has spread and can drop contact on bumps.
Tools: Flashlight, Pliers
Repair properly and road test
Replace the sensor if its own lead is damaged, or splice in harness with sealed solder connections, and re-clip the route so it cannot touch the tire. Clear the code and drive a route with bumps and tight turns.
Tools: Pliers, 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 |
|---|---|---|
| Re-clip and protect the sensor lead | Yes | $0–$80 |
| Replace left front wheel speed sensor (with lead) | Yes | $90–$300 |
| Splice-repair corroded harness section with sealed connectors | No | $100–$280 |
| Repair ABS module connector terminals | No | $120–$300 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Depends
C1155 doesn't affect the emissions part of a US smog check. In safety-inspection states an ABS light that is on during the check can fail the vehicle, even if it is intermittent.
Frequently asked questions
Why does C1155 come and go?
Most intermittent cases are a wire broken inside its insulation or a corroded connector. It conducts when the wheel is straight and opens when the steering turns or the suspension compresses.
The sensor measured fine. Can it still be the problem?
Yes. A resistance check on a still sensor can pass while the internal wire opens when flexed or hot. Measure while bending the lead, or swap in a known-good sensor.
Can I just solder the broken wire?
You can, if you use solder with heat-shrink sleeves and seal it against water. Twisted wires and electrical tape corrode quickly in the wheel well and will bring the code back.
Is C1155 the same as C0035?
They describe the same wheel. Ford uses C1155 for a left front circuit failure, while C0035 is the generic number many other makes use.
Sources
- Manufacturer public service information (cross-checked)
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy