C1873 — Air Suspension RF Air Spring Solenoid Output Circuit Failure

C1873 — Air Suspension RF Air Spring Solenoid Output Circuit Failure. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, poor ground connection, corroded, loose or damaged connector.

chassis (brakes/steering/suspension)

Is it safe to drive?

Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm C1873 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many C0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the air suspension RF air spring solenoid output circuit for damage, corrosion, chafing or poor contact.
Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm C1873 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for C1873 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000. Overall, fixing C1873 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How do I diagnose C1873 myself?

Start with a scan: confirm C1873, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the air suspension RF air spring solenoid output circuit, and verify the suspect component against live data before buying parts.

What is the most common cause of C1873?

The most common causes are: control module driver fault, poor ground connection, corroded, loose or damaged connector.

How much does it cost to fix C1873?

Repair wiring or connectors — $80–$250; Replace the faulty sensor or actuator — $150–$500; Control module repair — $300–$1,000. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of C1873?

Drivers most often notice: possible limp mode depending on the affected component, increased fuel consumption in some cases, Check Engine Light on, the affected system operates intermittently or not at all.

Is it safe to drive with C1873?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

When your scan tool pulls a C1873, the vehicle's control unit is reporting that something in the right-front air suspension circuit has stopped behaving the way it should. Specifically, this code points to the RF (right-front) air spring solenoid output circuit — the electrical pathway that tells the air suspension how much pressure to send to that corner of the car. The module expects to see a specific voltage range through that circuit, and C1873 means the signal has wandered outside those parameters.

The air suspension system on many luxury and heavy-duty vehicles uses solenoid valves to control air flow into and out of the springs at each wheel. The ECU or suspension control module constantly watches these circuits while you drive. If a problem persists long enough to clear the "tolerance window" over one or more complete drive cycles, the module logs C1873 and turns on the warning light. The freeze frame data captured alongside the code is gold — it records engine RPM, vehicle speed, load, and temperature at the exact moment the fault triggered, giving you the precise conditions to reproduce during diagnosis.

C1873 falls under the chassis category, which covers brakes, steering, and suspension. That broad classification makes sense here because the air spring is part of the vehicle's ride-height management system. When the right-front solenoid circuit fails, the module may still try to compensate using the remaining functional corners, or it could trigger a reduced-function limp mode depending on how the manufacturer programmed the system.

Symptoms of C1873

The Check Engine or suspension warning light stays illuminated
The affected air spring may not inflate, deflate, or hold pressure correctly
Ride height could appear lower or higher at the right-front corner compared to the others
In some cases, the system enters a limp-home mode limiting suspension adjustment
The vehicle may feel slightly stiffer or rougher over bumps on that corner
Fuel consumption can edge upward if the engine is working harder against an uneven stance
Intermittent operation — working one moment, failing the next — is common with electrical faults

What causes C1873

The root cause usually falls into one of four categories:

A failed driver inside the suspension control module that can no longer switch the solenoid on and off properly
A blown fuse or fusible link feeding power to that specific circuit
Wiring damage — an open circuit, a short to ground or battery voltage, or a connector that has pushed apart or corroded internally
A weak or oxidized ground connection at the solenoid or module, causing the circuit to read incorrectly
The solenoid valve itself could be internally shorted or open, though this is checked later in the process

How to diagnose C1873

Approach this systematically to avoid swapping expensive parts unnecessarily:

Plug in your OBD2 scanner and confirm C1873 is present. Record the freeze frame data — this snapshot tells you what the engine and vehicle were doing when the module first spotted the fault. Use those conditions as your target when road-testing later.
Pull all related diagnostic trouble codes.Codes that accompany C1873 often point to the real culprit — a shorted solenoid might generate multiple circuit codes, for example. Cross-reference any TSBs (Technical Service Bulletins) for your exact make, model, and model year; manufacturers sometimes publish software updates or known fixes for recurring C0xxx code patterns.
Visually trace the wiring harness running to the right-front air spring solenoid. Look for worn insulation, melted sections near hot exhaust components, broken strands inside the wire, moisture intrusion at connectors, and any signs of previous repairs that might have been done incorrectly.
Check the fuses and power feeds for that circuit. A simple blown fuse will set the same type of failure. Confirm the fuse is good and that power is present at the solenoid connector with the key on.
With the connector unplugged, measure the solenoid's resistance and inspect it for internal shorts or opens. Then probe the circuit for proper voltage and ground — both sides of the equation must be clean.
Perform a wiggle test on the harness while monitoring live data. If the signal drops out when you flex the wiring, you have found a broken or pinched wire that only fails under movement.

Repair options and costs

If the wiring and connectors look sound after inspection, you can move toward component replacement:

Wiring repair or connector replacement typically runs $80–$250 depending on whether you need to splice, replace terminals, or run a new section of harness
Replacing a faulty air spring solenoid valve (the actuator itself) generally costs $150–$500 for parts and labor
If the suspension control module's driver circuit has failed internally, module repair or replacement can reach $300–$1,000 depending on whether the unit is rebuilt or new and whether it requires programming

Total cost to fix C1873

Expect to spend anywhere from $80 on the low end — for a simple wiring fix or loose connector — up to $1,000 if the control module itself is shot. Most C1873 cases resolve in the $200–$500 range when the solenoid or its wiring is the culprit. Always verify the exact failure point before committing to a module replacement, because a bad solenoid is far cheaper to fix than an ECM.

Can you drive with C1873?

Yes — in most vehicles the car remains drivable, though the right-front corner may sit lower or ride firmer than it should. The safety systems tied to braking and steering are not directly affected by this code, so you won't lose control of the vehicle. That said, prolonged driving with a collapsed or dysfunctional air spring stresses the remaining components and can lead to additional failures. Treat any stalling, no-start condition, or warning lights for brakes and steering as urgent, but a standalone C1873 with a normal ride height is safe to drive short-term to your repair facility.