P1925 — Fuel Additive Level Supply Overvoltage

P1925 — Fuel Additive Level Supply Overvoltage. P1925 is not normally an immediate engine-stopping fault, but the excessive supply voltage can corrupt the additive-level input and prevent proper dosing.

For Ford vehicles

fuel additive level circuit – supply voltage too high

vehicle

Is it safe to drive?

Repair the additive-level circuit promptly P1925 is not normally an immediate engine-stopping fault, but the excessive supply voltage can corrupt the additive-level input and prevent proper dosing. Avoid extended driving if the additive warning remains active, the reservoir reading is implausible, or other fuel-management codes are present.

Typical symptoms

The check-engine light or a fuel-system warning may illuminate with P1925 stored
The displayed fuel additive level may appear incorrectly high, full, erratic, or unavailable
A low-additive warning may occur even when the additive reservoir is not low
Automatic fuel additive dosing may be disabled, intermittent, or incorrectly commanded
The vehicle may otherwise drive normally when no additional fuel-management faults are present

Common causes

A short to battery voltage in the fuel additive level sensor supply or reference wire
A corroded or damaged connector allowing power to leak into the level-sensing circuit
A defective fuel additive level sensor with an internal short or high-leakage failure
A failed voltage regulator, reference-voltage supply, or switching transistor in the additive-level circuit
An improper sensor ground causing the P1925 voltage signal to read falsely high
Charging-system voltage above specification or a less-common internal PCM driver failure

How to diagnose with an OBD scanner

Confirm P1925 with an OBD2 scanner Connect an OBD2 scanner such as an ELM327 adapter or AIScanAuto, then check stored codes, pending codes, and freeze-frame information. Confirm that P1925 is active and note any fuel additive or fuel-trim codes that could affect the diagnosis.
Inspect the additive-level wiring Using the vehicle wiring diagram, locate the fuel additive level sensor or circuit module. Inspect the connector and related harness for damaged insulation, pin-to-pin shorts, corrosion, water intrusion, and accidental contact with battery-voltage circuits.
Measure the supply voltage With the ignition state specified by service information, back-probe the additive-level supply and reference pins. Compare the readings with the manufacturer specification; voltage above the specified limit confirms the overvoltage condition identified by P1925.
Separate wiring and component faults Disconnect the level sensor or module and repeat the voltage test at its connector. Persistent excessive voltage points to the supply circuit, regulator, or a short to battery power, while normal disconnected voltage with an excessive connected reading suggests a defective sensor.
Repair, clear, and verify P1925 Repair the open, shorted, corroded, or defective wiring or component, restore proper grounds, and verify supply voltage is within specification. Clear the code with the scanner, repeat the ignition cycle, and confirm that P1925 does not return while monitoring the additive-level reading.

Approximate repair cost

An independent shop may charge roughly $90–$600 USD for P1925 diagnosis and the related wiring repair, connector service, or fuel additive level sensor/module replacement. These figures are estimates only and vary by region, vehicle configuration, parts availability, and labor time.

Common questions

Is it safe to drive with P1925 stored?

P1925 is generally a caution-level fault rather than an immediate stop condition, but incorrect additive-level voltage can disable or misdirect fuel additive dosing. Repair it promptly and avoid driving if other fuel-system or check-engine faults are also present.

What does P1925 specifically mean?

P1925 means the fuel additive level circuit has detected supply voltage above the allowable limit. The fault may involve the level sensor, its connector, a shorted harness, a bad ground, or a failed voltage supply.

Why does the additive level read incorrectly with P1925?

The overvoltage condition can overload the additive level sensor or distort the signal sent to the control module. The display may show full, empty, erratic, or unavailable even though the reservoir level has not changed.

Do I need to replace the sensor for P1925?

Not necessarily. Testing the supply voltage with the sensor disconnected can distinguish a wiring or regulator problem from an internally defective sensor. Replace the component only when the circuit checks are correct and the sensor still exceeds its specified voltage.

P1925 — ---

P1925 OBD2 Code: What It Means, Symptoms, Causes and How to Fix It

When your scan tool displays P1925, the engine or transmission control unit has detected that one or more sensor and actuator circuits are behaving outside their factory-calibrated operating range. The specific circuit involved varies by manufacturer and model, but the underlying problem is the same: the signal or power path that the ECU relies on to monitor or control a specific system has gone out of bounds. The module logs P1925 and turns on the Check Engine Light to alert you.

The ECU does not set this code on a single bad reading. Most control units require the fault to appear consistently over multiple drive cycles before logging a confirmed code. When it does confirm the failure, the module captures a freeze frame snapshot — a precise record of engine rpm, load, coolant temperature and vehicle speed the instant the problem occurred. Reviewing that snapshot before you start poking around is the single most effective way to shorten your diagnosis.

Common Symptoms of P1925

P1925 triggers a Check Engine Light, but the broader driving experience depends on which circuit is affected:

Check Engine Light illuminates and stays on
The affected system operates intermittently or stops working entirely
Possible limp-home (reduced-power) mode, especially if the fault involves a transmission or engine protection circuit
Noticeable increase in fuel consumption if the sensor affects air-fuel mixture, fuel delivery or shift scheduling
Other driveability complaints may surface depending on whether the fault touches throttle control, transmission operation or an emissions-related actuator

What Causes P1925?

Root causes span the full range from trivial to serious. Most shops find the problem on the wiring side before they ever touch a sensor:

Blown fuse feeding the circuit in question
Corroded, loose or physically damaged connector at the sensor or actuator
Control module driver fault — the module itself cannot properly switch the circuit
Poor or corroded ground connection feeding the affected component
Open or shorted wiring somewhere in the circuit harness
Faulty sensor or actuator that no longer produces or responds to the correct signal

How to Diagnose P1925

Effective diagnosis follows a logical path from easiest checks to more involved ones:

Connect your OBD2 scanner, confirm P1925 is stored, and save the freeze frame data. Note the engine rpm, load, coolant temperature and vehicle speed recorded at the moment of failure — replicate those conditions during your test drive.
Pull all other stored codes. Related codes pointing to the same circuit often reveal the root cause faster than chasing P1925 in isolation. Also search your manufacturer's TSB database by VIN for any open technical service bulletins; certain P1925 failures have factory-documented fixes or software updates.
Visually inspect the wiring harness and connectors associated with the fault circuit. Look for chafed insulation, broken strands, corrosion, bent pins and any signs of water intrusion.
Measure reference voltage, ground integrity and signal continuity at the component connector using a multimeter. Compare your readings to manufacturer specifications.
Perform a wiggle test on the harness while monitoring live data on your scan tool. Any signal dropout during movement points to a broken wire or intermittent connector.
Clear the code, complete a full drive cycle that reproduces the freeze frame conditions, and verify that P1925 does not return. If it comes back, the fault is still present.

How to Fix P1925

Address the most common and least expensive possibilities before replacing major components. Use your freeze frame data and symptom checklist to narrow the suspect list.

Repair Action	Typical Cost (Parts + Labor)
Repair wiring or connectors	$80 – $250
Replace faulty sensor or actuator	$150 – $500
Control module repair or replacement	$300 – $1,000

How Much Does It Cost to Fix P1925?

P1925 repair costs vary widely because the code describes a symptom rather than a single failed part. Independent shop labor rates typically run $80–$120 per hour depending on your region. Wiring repairs and connector cleaning or replacement usually fall between $80 and $250. If a sensor or actuator is confirmed faulty, expect $150–$500 for parts and installation. In the worst-case scenario where the control module itself has an internal driver failure, professional repair or replacement runs $300 to $1,000. In most cases, a thorough diagnosis costs far less than jumping straight to the most expensive repair option — and many P1925 faults turn out to be nothing more than a corroded connector or a blown fuse.

Can You Drive with P1925?

P1925 is classified as a short-term driving-safety concern. In most instances your vehicle remains operational, though you may notice reduced performance or a disabled auxiliary system. However, if the accompanying symptoms include stalling, a no-start condition, or warnings related to braking or steering, treat the situation as urgent and have the vehicle towed rather than driven.