P1924 — Low Fuel Additive Sensor Voltage

Does P1924 always mean the fuel additive tank is empty?

No. P1924 identifies low supply voltage in the fuel additive level circuit. An empty or low tank is a separate condition that may produce another code or a separate warning message.

Can I clear P1924 and continue driving?

Clearing P1924 only removes the stored code; it does not correct the voltage fault. Continue driving only if there is no low-additive, derate, or no-start warning, and arrange repair promptly.

How is the fuel additive level sensor voltage tested?

Use the vehicle wiring diagram to identify the correct pins, then back-probe supply and ground at the sensor connector with the ignition on and engine off. Compare the measured values with the manufacturer specification.

What if P1924 is present but connector voltage appears normal?

Check the circuit while moving the connector, inspect PCM power and ground paths, and look for intermittent harness damage. The fault may also disappear after warming up, so a static measurement may not reproduce the low-voltage condition.

When your vehicle's engine control unit detects a problem within the sensor and actuator circuit group, it sets trouble code P1924. This code indicates that one or more electrical components responsible for monitoring or controlling a specific system are behaving outside their expected parameters. Think of it as the ECU catching a conversation that has gone silent or started producing nonsense — it flags the issue, stores diagnostic information, and turns on the check engine light to alert you.

The control module does not wait for a single bad reading to trigger P1924. It watches the circuit over multiple drive cycles, comparing live sensor data and actuator feedback against factory-defined acceptable ranges. Only when the abnormality persists long enough to confirm a genuine fault does the module lock in the code. What makes P1924 particularly useful during diagnosis is the freeze frame snapshot saved alongside it — this recorded slice of data captures engine speed, load, temperature, and vehicle speed at the exact moment the fault occurred, giving you a precise starting point for troubleshooting.

Common Symptoms of P1924

• The affected system behaves erratically or stops functioning entirely during the drive cycle
• The check engine or malfunction indicator lamp stays illuminated on the dashboard
• Fuel economy may drop noticeably in some vehicle applications
• Reduced power mode (limp home) can engage depending on which circuit triggered the code
• In rare cases, secondary systems dependent on the faulty circuit may display intermittent operation

What Causes P1924?

• A driver circuit failure inside the powertrain control module itself
• Corrosion, looseness, or physical damage at the wiring connector junction
• An open or shorted wire somewhere in the affected circuit harness
• Loss of proper ground connection at the sensor or actuator mounting point
• A failed sensor, solenoid, or actuator component feeding incorrect data
• A blown fuse or power supply issue disrupting voltage to the circuit

How to Diagnose P1924

1. Plug in an OBD2 scan tool and retrieve all stored codes. Record P1924 and any accompanying codes, then save the freeze frame data associated with P1924 for reference during your road test.
2. Cross-reference any additional trouble codes — secondary codes often point directly to the root cause rather than the circuit group flagged by P1924. Check manufacturer technical service bulletins using your VIN on the automaker's website or the NHTSA database for known fixes or software updates.
3. Perform a thorough visual inspection of the wiring harness and connectors tied to the suspect circuit. Look for cracked insulation, greenish corrosion buildup, bent pins, or any signs that the connector is not seated securely.
4. With the connector unplugged, use a multimeter to verify reference voltage, proper ground resistance, and signal wire continuity from the ECU to the component. Compare your readings against factory specifications.
5. Conduct a wiggle test on the harness while monitoring live data on your scan tool or oscilloscope. Any signal dropouts or voltage fluctuations indicate a broken conductor hidden inside the insulation.
6. Clear P1924 after your inspection and repair work, then drive the vehicle through a complete drive cycle — specifically replicating the conditions stored in the freeze frame data — to confirm the code does not reappear.

Repair Options and Costs

Addressing the most common and least expensive culprits first keeps your repair bill manageable:

• Wiring harness repair or connector replacement: $80–$250
• Control module driver circuit repair or replacement: $300–$1,000
• Sensor or actuator replacement: $150–$500

Total Cost to Fix P1924

Actual repair costs hinge entirely on which component triggered the fault. At independent shop labor rates in the United States, you can expect to pay between $80 and $1,000 total depending on the diagnosis. Wiring fixes and connector work sit at the lower end, while full control module replacement or rebuilt unit installation pushes toward the upper range. The most cost-effective approach is always a confirmed diagnosis before purchasing parts — the worst-case scenario should never be your first assumption.

Can You Drive with P1924?

Severity level for this code is classified as short. In most instances, your vehicle remains drivable, though you may experience reduced performance from the affected system or notice that an auxiliary function has been disabled. However, if the malfunction causes engine stalling, a no-start condition, or interferes with braking and steering assist systems, stop driving immediately and arrange for diagnosis. Treat any associated safety warnings as urgent regardless of what the scan tool reports.