P0E87: Battery Charger B Voltage Sensor Circuit Low

What it means

The ECM detects a low fault on the battery charger b voltage sensor circuit. Reading cannot be used reliably for control.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The battery charger B voltage sensor sends a signal that the control module uses to manage charging. P0E87 sets when that signal is lower than expected, which can result from a signal wire short to ground, a failed sensor, or poor connector contact.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Internal sensor short
3. Connector pins corroded - high contact resistance

Symptoms

• Charge status indicator shows fault
• Charging may not start or interrupts
• Slower-than-expected charge rate

How to diagnose it

1. Check freeze-frame and live data to confirm the charger B voltage sensor signal is low and note whether charging was active.
2. Inspect the sensor connector for corrosion, moisture, loose pins, or poor terminal contact.
3. Check the signal wire for a short to ground and inspect the harness for chafing or crushed sections.
4. Verify the sensor’s supply and ground, then compare its output with the actual circuit voltage using the manufacturer’s procedure.
5. If wiring and connections are sound, test the sensor and charger B according to the manufacturer’s specification.

Common fixes

• Clean and secure corroded or loose connector terminals.
• Repair a signal wire short to ground or damaged harness section.
• Replace the voltage sensor if its output remains low with correct wiring and supply.
• Repair charger B if the sensor circuit tests correctly but the fault persists.

Can I keep driving?

Charging may be interrupted or unavailable, so check that the battery has enough charge before driving and do not depend on charger B completing a session. If the vehicle displays a high-voltage system warning, follow its instructions and arrange prompt diagnosis.