Standardized generic DTCComputer & output circuits

P0625 — Generator Field/F-Terminal Circuit Low

P0625 is the standardized powertrain DTC for “Generator Field/F-Terminal Circuit Low.” The code identifies the monitored condition; it does not by itself prove which part failed.

Standardized generic definition

Generator Field/F-Terminal Circuit Low

DTC category

Computer & output circuits

Diagnostic priority

Moderate to high. Low system voltage can create many secondary DTCs and may cause stalling/no-start; excessive voltage can damage electronics.

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What P0625 means

P0625 is the standardized powertrain DTC for “Generator Field/F-Terminal Circuit Low.” The code identifies the monitored condition; it does not by itself prove which part failed.

Start with the stored data and the simplest external checks before replacing the component named in the code.

How to interpret the code wording

“Circuit Low” means the module saw voltage or a signal below its calibrated range. Depending on circuit design, likely test paths include a short to ground, missing reference/supply voltage, excessive resistance, poor terminal contact, or a failed sensor/actuator. Verify the circuit diagram and measure the circuit before replacing the named component.

Possible symptoms

Battery/charging warning
Slow crank or no-start
Multiple unrelated warning lights/DTCs
Electrical accessories behaving abnormally

Causes to test

These are diagnostic possibilities, not a statistical parts-replacement ranking. Vehicle-specific service information takes priority.

Weak battery or poor terminal connection
Alternator/generator fault
Drive belt/tensioner issue
Poor engine/body grounds or charging cable connection
Generator control circuit or module fault

Step-by-step diagnostic workflow

Test battery state of charge and terminal condition first.
Measure cranking voltage and charging voltage under load.
Inspect belt drive and voltage drop across positive/ground cables.
If smart charging is used, review commanded generator output and battery-sensor data.
Resolve system-voltage faults before diagnosing secondary communication/sensor codes.
Clear codes only after repair, then complete an appropriate drive cycle and verify the code and symptoms do not return.

Preserve evidence: EPA OBD guidance emphasizes that stored DTCs and freeze-frame data are important to proper diagnosis. Save them before clearing codes.

Scan data worth checking

Battery/system voltage
Generator command/load
Battery current sensor where equipped
Voltage during crank

Severity and drivability

Moderate to high. Low system voltage can create many secondary DTCs and may cause stalling/no-start; excessive voltage can damage electronics.

Stop driving and investigate immediately if there is a flashing MIL, oil-pressure warning, overheating, fuel leakage, severe misfire, major loss of power, abnormal mechanical noise, or a transmission that is slipping badly.

Common diagnostic mistakes

Replacing modules while system voltage is unstable
Testing only open-circuit battery voltage
Ignoring ground voltage drop

Related generic codes

P0626 — Generator Field/F-Terminal Circuit HighP0623 — Generator Lamp Control CircuitP0622 — Generator Field/F-Terminal CircuitP0621 — Generator Lamp/L-Terminal CircuitP0620 — Generator Control Circuit MalfunctionP0563 — System Voltage High

Source and accuracy notes

Generic DTC structure and standardized definitions are governed by SAE J2012/J2012DA. Actual enable criteria, thresholds, circuit pinouts, test values, software conditions, and repair procedures vary by vehicle. Use current OEM service information for the exact year/engine/calibration and check applicable manufacturer technical service bulletins. See the site methodology and primary-reference policy.