Corroded, loose, or damaged wiring or connector terminals at the battery charger B voltage sensor; Faulty battery charger B voltage sensor itself, especially if it has been exposed to heat or moisture; Poor ground connection for the sensor or the charger assembly; Internal fault in the battery charger module causing an unstable reference voltage; PCM software calibration issue or internal PCM driver fault on the sensor circuit; Electrical interference from nearby high-current cables or aftermarket accessories

DTC codes / P0Exx · Hybrid propulsion / P0E89

P0E89Battery Charger B Voltage Sensor Circuit Intermittent/Erratic

P0E89 means the powertrain control module (PCM) has seen the voltage signal from the battery charger B voltage sensor jump around or drop out intermittently, rather than holding a steady value. The sensor monitors the charger's output, and the PCM flags this code when the signal is erratic for a calibrated amount of time or number of ignition cycles.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light or service vehicle soon message
Often no symptoms besides the warning light, especially if the fault is intermittent
Charging system warning lamp may flicker or stay on if the charger stops working
Battery may not hold a charge or may go flat overnight if the charger fails to engage
Reduced electric-only range or slower charging on plug-in hybrid vehicles
Possible electrical accessories behaving erratically if system voltage fluctuates

Common causes, most likely first

Corroded, loose, or damaged wiring or connector terminals at the battery charger B voltage sensor
Faulty battery charger B voltage sensor itself, especially if it has been exposed to heat or moisture
Poor ground connection for the sensor or the charger assembly
Internal fault in the battery charger module causing an unstable reference voltage
PCM software calibration issue or internal PCM driver fault on the sensor circuit
Electrical interference from nearby high-current cables or aftermarket accessories

How to diagnose and fix it

Inspect the sensor connector and harness for corrosion, chafing, or loose pins, and clean or repair as needed
Check the sensor ground circuit for excessive resistance and repair any bad ground
Back-probe the sensor signal wire and monitor voltage with a multimeter or oscilloscope while wiggling the harness to catch intermittent faults
Compare the sensor reading with a known-good reference or scan tool live data to confirm erratic behavior
Replace the battery charger B voltage sensor if the signal is erratic and wiring is proven good
Check for technical service bulletins or software updates for the PCM or charger module
Clear the code and perform a road test or charging cycle to verify the repair

Intermittent sensor faults that fool technicians

A loose ground at the charger assembly often mimics a failed sensor, so always load-test the ground circuit before condemning parts.
The code can set from a momentary voltage spike during engine cranking, so check for a weak battery or starter draw before chasing the sensor.
On some vehicles the charger B voltage sensor is integrated into the charger module and cannot be replaced separately, requiring module replacement.
Intermittent faults often leave no freeze-frame data, so a wiggle test with a graphing multimeter is more reliable than a static code read.
Aftermarket accessories wired near the charger harness can introduce electrical noise that the PCM interprets as an erratic sensor signal.

Can I keep driving with P0E89?

You can usually drive the vehicle, but avoid long trips or heavy electrical loads until the fault is repaired, because an intermittent charger fault can leave you with a flat battery or reduced hybrid function. If the charging system warning lamp is on or the battery voltage is dropping, stop driving and seek service.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.