C1873 — Air Suspension RF Air Spring Solenoid Output Circuit Failure #

The description of code C1873 may vary depending on the vehicle manufacturer (OEM). Always consult your service manual for the exact terminology and troubleshooting steps for your specific make and model.

Known description variations:

• Air Suspension Front Right Air Spring Solenoid Circuit Malfunction (Ford, Lincoln, Mercury)
• RF Air Spring Solenoid Circuit Fault (Land Rover)
• Front Right Air Spring Solenoid Output Circuit Error (Jaguar)
• Right Front Air Suspension Solenoid Circuit Abnormal (Hyundai, Kia)

Summary of DTC C1873 #

The C1873 diagnostic trouble code (DTC) indicates a malfunction in the output circuit controlling the right front (RF) air spring solenoid of the air suspension system. This solenoid is responsible for regulating the air pressure in the right front air spring, helping the system adjust ride height and comfort. When the vehicle’s suspension control module (sometimes called the Electronic Suspension Control Module, or ESCM) detects an unexpected voltage or current in the output circuit, it sets this code and may trigger a warning light. Depending on the vehicle, this may result in deactivation of the air suspension or a “suspension fault” message on the dashboard. Addressing this code quickly helps ensure ride quality and prevents further suspension damage.

Frequent Symptoms for DTC C1873 #

If your vehicle logs the C1873 code, you may notice several symptoms affecting both ride comfort and handling. These symptoms can range from subtle to severe, especially if the air suspension defaults to a fail-safe mode. Common signs include:

• Noticeable sagging or uneven height of the right front corner of the vehicle
• Illuminated suspension warning light or message in the instrument cluster
• Unusual noises from the right front suspension area (hissing, clicking, or compressor cycling)
• Stiff or harsh ride quality, particularly on rough roads
• Vehicle leaning to one side during driving or while parked
• Disabling of adjustable ride height features

Probable Causes for DTC C1873 #

The C1873 code is typically triggered when the suspension control module detects an electrical problem with the right front air spring solenoid output circuit. While several issues can cause this, some are more common than others. Here are the most likely culprits, in order of frequency:

1. Wiring faults (corroded, broken, or shorted wires in the harness to the RF air spring solenoid)
2. Faulty right front air spring solenoid (internal failure or poor electrical connection)
3. Loose or corroded electrical connectors at the solenoid or control module
4. Damaged or failed air suspension control module (rare)
5. Blown fuse or relay related to the air suspension system

Step-by-Step Diagnosis for C1873 #

Diagnosing C1873 requires a methodical approach to distinguish between wiring, component, and control module faults. Before replacing any parts, follow these essential steps:

• Verify the code and clear it: Use a professional scan tool to confirm C1873 is active and attempt to clear it. If it returns, proceed.
• Inspect ride height and visual symptoms: Check if the vehicle is sitting unevenly or if there are visible signs of air spring deflation at the right front corner.
• Check related fuses and relays: Ensure all air suspension fuses and relays are intact and properly seated.
• Examine wiring and connectors: Visually inspect the harness and connectors leading to the RF air spring solenoid for signs of corrosion, damage, or water intrusion.
• Test solenoid operation: With a multimeter, check for proper voltage supply and ground at the solenoid. Measure the solenoid’s resistance to confirm it matches OEM specs.
• Perform a continuity test: Check continuity between the control module and the RF solenoid to rule out open or shorted circuits.
• Swap components (if possible): On some vehicles, swapping RF and LF (left front) solenoids can help isolate the problem.
• Check control module output: If all wiring and solenoid tests pass, the control module may not be providing the correct output signal and could require further diagnosis or replacement.

Possible Repairs for C1873 #

Once you’ve identified the root cause, repairs will target the faulty component or wiring. The most common fixes for C1873 include:

• Repair or replace damaged wiring in the right front air spring solenoid circuit
• Replace the right front air spring solenoid if it is out of specification or non-functional
• Clean or replace corroded connectors at the solenoid or control module
• Replace blown fuses or defective relays related to the air suspension
• Replace the air suspension control module (only after confirming all other components are functioning properly)

Is It Safe to Drive With Code C1873? #

Limited — Not Recommended for Extended Use. While you may be able to drive short distances with code C1873 present, it’s not advisable to ignore it. The vehicle’s right front suspension may be compromised, leading to uneven ride height, reduced stability, and accelerated tire wear. In some cases, the air suspension system may enter a fail-safe mode, resulting in a very stiff ride and limited handling. For safety and to prevent further damage, address this issue as soon as possible.

Vehicles Most Commonly Affected by C1873 #

This code appears most frequently on vehicles equipped with OEM air suspension systems, especially those with advanced electronic ride control. The following makes and models are commonly reported:

• Ford Expedition, Lincoln Navigator, Mercury Mountaineer (2003–2014)
• Land Rover Range Rover, Discovery, LR3/LR4 (2005–2016)
• Jaguar XJ, X350, X358 (2004–2009)
• Hyundai Genesis, Equus (2009–2015)
• Kia K900, Mohave

Frequent Errors & Best Practices for C1873 #

Avoiding misdiagnosis and unnecessary parts replacement is crucial when dealing with air suspension DTCs. Here are common mistakes and tips for a successful repair:

• Ignoring wiring issues: Many technicians replace the solenoid without checking the wiring harness, only to have the problem return.
• Overlooking corroded connectors: Moisture intrusion at connectors is a leading cause, especially in climates with heavy rain or road salt.
• Not performing a continuity test: Relying solely on visual inspection can miss hidden breaks or shorts in the wiring.
• Skipping fuse and relay checks: Power supply issues are often overlooked but are easy to test early in the diagnostic process.
• Replacing the control module prematurely: The module is rarely at fault; replace it only after confirming all wiring and solenoid components are good.

Quick FAQ for DTC C1873 #

Still have questions about this code? Here are answers to some of the most common concerns:

• Q: Will resetting the code fix the problem?
  A: Clearing the code may temporarily turn off the warning, but if the underlying fault is not resolved, C1873 will return. Always diagnose and repair the root cause.
• Q: Can I bypass the air suspension solenoid to avoid the fault?
  A: Bypassing the solenoid is not recommended. Doing so can disrupt the air suspension system, compromise vehicle safety, and trigger additional fault codes.