C1171 — Rear Right Wheel Speed Signal Fault

C1171 — Rear Right Wheel Speed Signal Fault. C1171 can leave ABS or traction control impaired even if ordinary braking still feels normal.

For Ford vehicles

rear right wheel speed sensor input signal

vehicle

Is it safe to drive?

Prompt diagnosis recommended C1171 can leave ABS or traction control impaired even if ordinary braking still feels normal. Arrange prompt inspection, avoid relying on ABS during emergency braking, and do not continue driving if the ABS light flickers, braking feels abnormal, or the code repeatedly returns.

Typical symptoms

The ABS warning light illuminates and C1171 is stored in the control module
ABS or traction control may intervene unexpectedly or remain unavailable
Vehicle stopping distance can increase on loose, wet, or slippery surfaces
An intermittent C1171 may cause the ABS light to flicker or the fault to clear temporarily

Common causes

A faulty rear right wheel speed sensor with an open, shorted, or intermittent internal circuit
Damage, chafing, or corrosion in the rear right wheel speed sensor wiring harness
A loose, cracked, or corroded rear right wheel speed sensor connector
A damaged or obstructed rear right tone ring, reluctor wheel, or encoder ring where equipped
Excessive clearance at the rear right wheel speed sensor caused by a loose sensor, hub movement, or worn bearing
An internal input fault in the ABS control module after the wiring and sensor have been verified

How to diagnose with an OBD scanner

Confirm C1171 and monitor live wheel data Connect an OBD scanner, such as an ELM327 interface used with AIScanAuto, and read stored and pending ABS codes. If live data is available, compare the rear right wheel speed value with the other wheels while the vehicle is safely supported and the wheel is turned slowly. A dropout or implausible rear right reading supports the C1171 signal diagnosis.
Inspect the rear right sensor area With the ignition off, inspect the rear right sensor, mounting point, connector, and wiring near the hub. Look for physical damage, heat discoloration, corrosion, trapped road debris, or a connector that is not fully seated. Also inspect the tire and suspension components for contact with the sensor cable.
Check the sensor circuit Use the applicable wiring diagram to test the sensor power, ground, and signal paths for continuity, short circuits, and excessive resistance. Perform a wiring wiggle test while monitoring the scanner for C1171. Do not assume the sensor is faulty merely because the code is present.
Verify sensor fit and tone ring condition Confirm that the rear right sensor is correctly mounted and that its air gap meets the vehicle specification. Inspect the tone ring or reluctor for cracked, missing, or obstructed teeth and check for excessive hub or bearing play. Replace damaged components rather than relying on repeated code clearing.
Clear and validate the repair After correcting the fault, clear C1171 with the scanner and perform a controlled road test while monitoring wheel-speed data. Confirm that the rear right value remains consistent with the other wheels and that no ABS, traction, or stability-control warning returns. If the fault remains with verified wiring, sensor, and ring, continue diagnosis at the ABS module input.

Approximate repair cost

A rough independent-shop estimate is USD 150-700 for diagnosis and likely repair, depending on whether the rear right sensor, connector, wiring, tone ring, bearing, or ABS input requires service. These figures are estimates and vary by region, vehicle design, labor time, and parts availability.

Common questions

What does C1171 specifically identify?

C1171 identifies an abnormal rear right wheel speed input signal, usually involving the sensor, its wiring or connector, or the associated tone ring and ABS input.

Can the vehicle be driven with C1171 stored?

Driving may be possible if ordinary braking feels normal, but ABS and traction control may be impaired. Prompt diagnosis is recommended, especially in rain, snow, or other low-grip conditions.

Does C1171 always mean the wheel speed sensor needs replacement?

No. C1171 can also result from damaged wiring, a loose connector, a defective tone ring, excessive sensor clearance, hub movement, or an ABS module input problem.

How should C1171 be diagnosed before replacing parts?

Use an OBD scanner to confirm the code and monitor rear right wheel-speed data, then inspect and electrically test the sensor circuit, connector, mounting, and tone ring before condemning the sensor or ABS module.

C1171 — C1171 — Manufacturer Controlled DTC: Causes, Symptoms & Fix

When your scan tool pulls code C1171, the vehicle's control module is reporting that a sensor or actuator circuit is behaving outside its expected parameters. The full description for C1171 reads "Manufacturer Controlled DTC," which simply means the fault falls within a category controlled by the automaker rather than being a generic OBD2 code. The powertrain or body control module monitors specific circuits and logs C1171 the moment those circuits stray from factory calibration windows.

The affected system varies depending on which sensor or actuator triggered the fault, but the underlying mechanism stays the same. Your vehicle's computer continuously compares real-world readings against acceptable ranges stored in its software. When a signal disappears, spikes, or drops below minimum thresholds, the ECU flags the condition. C1171 doesn't light up on the first hiccup, though—the module needs to confirm the fault persists under specific driving conditions before activating the Check Engine light. This staged approach prevents false alarms from transient electrical noise.

That brings us to freeze frame data. Whenever C1171 sets, your scanner captures a snapshot of engine operating conditions at the exact moment of failure: engine load percentage, RPM, coolant temperature, vehicle speed, and more. This information is gold when diagnosing intermittent problems. If the snapshot shows the engine at 3,200 RPM and 65 mph with 85% load, you now know exactly what conditions to replicate during testing.

Common Symptoms of C1171

The Check Engine light is the most obvious indicator that C1171 has set, but symptoms vary depending on which circuit triggered the fault:

The affected component operates intermittently or stops working entirely
Noticeable increase in fuel consumption due to the engine compensating for bad sensor data
The vehicle may enter limp mode, limiting power and speed to protect drivetrain components
Some auxiliary systems (climate control, traction, stability) may disable or behave erratically
In rare cases, you might notice rough idle or hesitation under acceleration
The symptom may come and go, making the problem harder to pin down without freeze frame data

What Causes C1171

C1171 typically stems from electrical problems rather than mechanical failures. The most common culprits, ranked by frequency:

Poor ground connection — Grounds degrade over time from corrosion, vibration, or loosened fasteners, causing signal instability
Open or shorted wiring — Broken insulation, pinched wires, or melted harnesses interrupt the electrical circuit
Corroded, loose, or damaged connectors — Moisture intrusion and thermal cycling weaken terminal contacts
Blown fuse — A failed fuse cuts power to the affected circuit entirely
Control module driver fault — The module's internal circuitry that drives the sensor or actuator has failed internally
Failed sensor or actuator — The component itself has reached end of life and stopped producing or receiving valid signals

How to Diagnose C1171

A systematic approach keeps you from replacing good parts. Follow these steps in order:

Connect your OBD2 scanner, confirm C1171 is stored, and record all freeze frame data. This snapshot tells you engine conditions when the fault occurred—replicate those conditions during your test drive.
Scan for additional trouble codes. C1171 often accompanies other sensor or circuit codes that point directly to the root cause. Check manufacturer TSB databases for known issues on your specific make and model.
Visually inspect the wiring harness and connectors tied to the affected circuit. Look for damaged insulation, chafing from contact with sharp edges, corrosion buildup on terminals, and any connectors that aren't fully seated.
Check reference voltage, ground integrity, and signal continuity at the component connector using a multimeter. Compare your readings against manufacturer specifications.
Perform a wiggle test on the harness while monitoring live data. Any signal dropouts or spikes indicate broken wires inside the insulation.
Clear the code, complete a full drive cycle including the exact conditions from your freeze frame data, and verify C1171 does not return.

Repair Options and Costs

Start with the cheapest, most common fixes before considering component replacement:

Repair wiring or connectors — $80–$250 for parts and labor; this fixes the majority of C1171 cases
Replace the faulty sensor or actuator — $150–$500 depending on the component and your vehicle
Control module repair or replacement — $300–$1,000 for professional service or unit replacement

How Much Does Fixing C1171 Cost?

Depending on which part actually failed, your total bill can vary significantly. Parts and labor at independent shop rates in the United States typically break down as follows: wiring and connector repairs run $80–$250, sensor or actuator replacement costs $150–$500, and control module service ranges from $300–$1,000. Most C1171 repairs fall somewhere between $80 and $1,000 total. An accurate diagnosis before purchasing any parts is the single best way to keep costs down—the most expensive component is rarely the one you should check first.

Can You Drive with C1171?

Severity is classified as short, meaning most vehicles remain drivable after this code sets. You may experience reduced performance or lose function of certain auxiliary systems, but the car will generally get you where you need to go. However, if C1171 triggers stalling, a no-start condition, or warning lights related to braking or steering, treat it as urgent and have the vehicle towed to a repair facility immediately.