P0625 — Generator Field/F Terminal Circuit Low

OBD2 code P0625 flags a problem with the sensor and actuator circuits (generator field/f terminal circuit low). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, poor ground connection, open or shorted wiring in the circuit.

powertrain (engine/transmission)

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 P0625 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 P0xxx 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 generator field/f terminal for damage, corrosion, chafing or poor contact.
Subsystem check Check for supply voltage at the generator field/f terminal connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
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 P0625 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0625 (parts and labor, USD, independent shop rates): Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000; Repair wiring or connectors: $80–$250. Overall, fixing P0625 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

Is it safe to drive with P0625?

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.

What are the symptoms of P0625?

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

Will P0625 clear itself?

Sometimes P0625 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of P0625?

The most common causes are: corroded, loose or damaged connector, poor ground connection, open or shorted wiring in the circuit.

How do I diagnose P0625 myself?

Start with a scan: confirm P0625, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the generator field/f terminal, and verify the suspect component against live data before buying parts.

Understanding P0625: Generator Field/F Terminal Circuit Low

P0625 is an OBD2 diagnostic trouble code that points to a problem with the generator's field circuit — specifically the "F" terminal. When your vehicle's engine control unit (ECU) detects that voltage on this circuit has dropped below acceptable levels, it logs P0625. This code falls under the powertrain category, meaning it relates to the engine or transmission control systems.

The generator (alternator) in your vehicle does more than just charge the battery. Its field circuit controls output voltage regulation — it tells the alternator how much power to generate based on current demand. The ECU monitors this circuit constantly. When everything works as it should, the field terminal carries a specific voltage signal. P0625 triggers when that signal stays suspiciously low — essentially reading close to ground potential when it shouldn't be.

Several things can cause this condition. A wire with damaged insulation may short to metal somewhere in the harness. Power supply to the field terminal might be interrupted entirely. Or a failing component could be pulling the circuit down. The ECU doesn't set P0625 on a single bad reading — it watches the circuit over multiple drive cycles before confirming the fault. Once triggered, the ECU also saves a freeze frame snapshot capturing RPM, engine load, coolant temperature, and vehicle speed at the moment of failure. That data is gold for anyone working through the diagnosis.

Symptoms of P0625

Check Engine Light illuminates on the dashboard
Affected electrical system operates intermittently or fails entirely
Some vehicles experience noticeably higher fuel consumption
Possible limp-mode activation depending on which system is affected
Headlights or interior lights may dim under electrical load
Battery may drain faster than normal or go dead after short parked periods

Common Causes of P0625

Signal wire shorted to ground due to damaged or chafed insulation
Missing supply voltage reaching the generator field/F terminal
Failed generator field terminal internally dragging the circuit low
Corroded, loose, or physically damaged electrical connector at the alternator
Poor ground connection somewhere in the charging circuit
Blown fuse protecting the field circuit from overload
Open or intermittently broken wiring within the harness itself

How to Diagnose P0625

Connect an OBD2 scanner, verify P0625 is stored, and record the freeze frame data — it shows exactly what was happening when the fault occurred.
Look for any related diagnostic trouble codes. Sometimes a different code points directly to the root cause. Check manufacturer TSBs for your make and model using your VIN — factory bulletins often document known issues and available software updates.
Inspect the wiring harness and connectors related to the generator field terminal. Look for worn insulation, corrosion buildup, broken wires, or connectors that aren't fully seated.
Test for supply voltage at the generator field terminal first. Then check resistance from the signal wire to ground — a reading close to zero ohms means you have a short to ground in the harness.
Verify reference voltage, ground integrity, and signal continuity at the component connector and at the ECU side.
Perform a wiggle test on the harness while watching live data — any signal dropouts indicate a broken wire or loose connection.
Clear the code, complete a drive cycle matching the conditions from the freeze frame, and confirm P0625 does not return.

Repair Options for P0625

Fix the cheapest and most likely causes before swapping expensive components:

Wiring harness or connector repair: $80–$250
Replace faulty sensor or actuator: $150–$500
Control module diagnosis and repair: $300–$1,000

Total Repair Cost

The final bill depends entirely on which part is actually faulty. At independent shop rates, wiring repairs typically run $80–$250 including parts and labor. Sensor or actuator replacement generally falls between $150 and $500. Control module work — whether repair or replacement — can reach $300 to $1,000 depending on the vehicle. Most P0625 repairs end up costing between $80 and $500. Spending time on accurate diagnosis first almost always saves money — the most expensive scenario is rarely the first place you should look.

Can You Drive with P0625?

Severity: Short. In most cases your vehicle remains driveable, though you might notice reduced performance or a disabled auxiliary feature. Watch for stalling, failure to start, or warnings related to brakes and steering — those symptoms turn this from a nuisance into an urgent issue. Otherwise, a short trip to a repair facility is reasonable without excessive risk.