P2E91

Code

Generic P — Powertrain

Battery Charger B Internal Power Supply Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 28 RU: 19

AI status

Completed

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Page language: EN

Causes

Loose, corroded or damaged electrical connectors to the charger
Blown fuse or failed relay in the charger power/ignition/feed circuit
Intermittent or high-resistance ground at the charger
Internal regulator or power-stage component failure inside the charger module
Faulty battery (low state of charge, high internal resistance) or main battery pack condition limiting charger operation
Software/firmware fault or mismatch in charger control unit

Symptoms

Charging rate reduced or unavailable from Charger B
Battery/charging system warning indicator illuminated on dash
Erratic charger behavior (starts/stops) or other charger-related DTCs present
Vehicle enters limp-home or reduced charging mode
Stored freeze-frame data showing abnormal supply rail voltages or currents

What to check

Retrieve all related DTCs and freeze-frame data with a scanner; record live data during fault conditions
Visually inspect Charger B connectors, wiring, and harness for damage, corrosion, or water ingress
Check fuses and relays for the charger power feed and control circuits
Verify good chassis and module grounds at the charger mounting point
Measure main battery pack voltage and state-of-charge before and during attempted charging
Confirm CAN/communication integrity between charger and vehicle ECU (no bus errors)

Signal parameters

Main battery/pack voltage — compare to vehicle specification during charge attempt
Module supply rails (internal charger rails such as 5V, 3.3V or manufacturer-specified rails) — should be within manufacturer tolerance
Charger input current and output current (charging current) — should follow commanded setpoint
Charger temperature sensor readings and overtemperature flags
CAN/serial messages: charger status, error codes and commanded charge rates (verify normal communication)
Ground resistance at charger mounting point — typical target: very low ohms (consult vehicle spec)

Diagnostic algorithm

Use a scan tool to read P2E91 and any related codes; save freeze-frame and live data of voltages/currents when the fault sets.
Visually inspect Charger B connector, wiring harness, and mounting for damage, corrosion, or moisture. Repair or secure as needed.
Check all fuses and relays in the charger power and control circuits; replace suspected faulty items and retest.
Verify battery/pack condition and state-of-charge; confirm the battery can accept charge and has healthy voltage under load.
Measure module supply rails at the charger connector (and at internal service points if allowed by manufacturer) with a multimeter/oscilloscope while recreating the fault. Compare to specs.
Confirm good ground: measure voltage drop to chassis while charging and inspect ground strap integrity. Repair ground connections if excessive.
Check CAN/communication lines for errors; if communications are lost or noisy, trace wiring and check termination resistors and bus integrity.
If external circuits and communications are good but internal rails are out of spec, consider charger module internal failure — consult manufacturer procedures for module repair or replacement.
After repairs, clear codes and perform a full system charging test; verify no reoccurrence and document measured parameters.

Likely causes

Loose/damaged connector or harness to Charger B
Blown fuse or failed power relay feeding Charger B
High-resistance ground at charger
Internal charger regulator or power electronics failure

Fault status

⚠️ Status

Battery Charger B internal power supply performance out of range — charger may be disabled or charging limited. Inspect power, ground, connectors, and charger module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.0 hours