P065B

Generator A Control Circuit Range/Performance

Q: Is it safe to drive with P065B?

Only briefly. If charging is unstable the battery can drain and the car may stall. Get the charging system tested soon.

Q: Can I just clear P065B?

It returns while the control circuit or alternator is out of spec. Test the charging system and repair the wiring first.

Charging system Generic OBD-II High

What it means

P065B means the PCM commanded the generator (alternator) control circuit but the resulting charging performance didn't match what it expected. That can leave the system undercharging or charging erratically, showing up as a battery light, dim lights, and eventually a discharged battery or stall. Check the control wiring and connector, then test the alternator's regulated output.

High

Can I keep driving? Limited — charging may be unstable, which can drain the battery and eventually stall the car. Have it checked promptly.

Real-world scan data

Seen in

144

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Appears alongside · share of P065B scans

P065Cin 36.1% 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 or charging warning light on
Check-engine light on
Dim or flickering lights, unstable charging voltage
Weak battery, hard starting, or stalling if it discharges

Common causes

Most likely first

Faulty generator/alternator (or its internal regulator)Likely
Open, shorted, or high-resistance generator control wiringCommon
Corroded or loose connector in the control circuitCommon
PCM control-circuit fault (less common)Less often

How to diagnose & fix

Work through it in order

Measure charging voltage at idle and under load — it should stay in the normal regulated range.
Inspect the generator control (field) wiring and connector for corrosion, opens, or high resistance.
Check the charging cables and grounds for voltage drop.
Replace the alternator if it can't hold regulated output with good wiring. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P065B?+

Only briefly. If charging is unstable the battery can drain and the car may stall. Get the charging system tested soon.

Can I just clear P065B?+

It returns while the control circuit or alternator is out of spec. Test the charging system and repair the wiring first.

Read & clear P065B 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