P0626

Generator Field/F Terminal Circuit High

Charging / electrical Generic OBD-II High

What it means

P0626 means the ECM sees excessive voltage on the alternator's field (F) terminal control circuit — the line it uses to regulate charging output. With this circuit reading high, charging can become unregulated, draining or overcharging the battery and upsetting the electrical system. It usually points to the alternator or its field wiring rather than the ECM.

High

Can I keep driving? Risky — the charging system may not be regulating properly, so the battery can drain or overcharge, leading to stalling or a no-start. Get the charging system checked promptly.

Real-world scan data

Seen in

651

scans in the past year

Found in

0.1%

of scans

0.2%

of scans that found faults

Appears alongside · share of P0626 scans

C0010in 12.0% of scans

C0218in 12.0% of scans

U3100in 12.0% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Battery/charging warning light on
Discharged or repeatedly dead battery
Dim or flickering lights and other electrical glitches
Stalling or hard starting

Common causes

Most likely first

Failing alternator/generator or its internal regulatorLikely
Damaged or shorted wiring on the field (F) terminal circuitCommon
Loose or corroded charging-circuit connectionsCommon
Poor ECM ground affecting field control (less common)Less often
ECM fault (checked last)Less often

How to diagnose & fix

Work through it in order

Load-test the battery and measure charging voltage at idle (roughly 13.5–14.7V) to gauge charging-system health.
Inspect the generator field/F terminal wiring and connector for a short to voltage, chafing, or corrosion.
Check the ECM control side of the field circuit against the manufacturer's spec.
Replace the alternator/generator if it can't regulate output with good wiring.
Clear the code and re-test charging under load; suspect the ECM only if everything else checks out.

FAQ

Quick answers

Is it safe to drive with P0626?+

Only briefly. If charging isn't regulating, the battery can drain and leave you stranded, or overcharging can harm electronics. Have it checked soon.

Can I just clear P0626?+

Clearing won't fix a charging fault — it returns and you risk a dead battery. Diagnose the generator and field circuit first.

Read & clear P0626 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX