A failing or internally faulty battery monitor module, often due to heat, vibration, or water intrusion.; Corroded, loose, or damaged wiring and connectors between the battery monitor module and the battery, body ground, or data bus.; A weak or aging 12-volt battery that causes the monitor to report implausible data and set a performance code.; Software or calibration issues in the battery monitor module or engine control module requiring a reprogramming update.; Poor ground connections at the battery negative terminal or chassis, leading to voltage drop that confuses the monitor.; A faulty current sensor or voltage sensing circuit inside the battery monitor module.; Communication faults on the controller area network (CAN) bus that intermittently disrupt data from the battery monitor module.

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P058A

P058ABattery Monitor Module Performance

Q: What does code P058A mean?

Battery Monitor Module Performance. P058A indicates that the battery monitor module, which is the dedicated controller that tracks the state of charge and health of the 12-volt battery, has reported an internal performance fault to the engine control module. The computer has detected that the module's own self-diagnostics have failed or that its calculated battery data is outside the expected range for the operating conditions.

P058A indicates that the battery monitor module, which is the dedicated controller that tracks the state of charge and health of the 12-volt battery, has reported an internal performance fault to the engine control module. The computer has detected that the module's own self-diagnostics have failed or that its calculated battery data is outside the expected range for the operating conditions.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the battery/charging system warning light or the check engine light, often with no other noticeable symptoms.
Inconsistent or missing battery state-of-charge information on the dashboard or infotainment display.
Intermittent electrical gremlins such as dimming lights, slow cranking, or accessories resetting, especially after the vehicle sits.
Automatic idle stop-start system may be disabled or behave erratically because it relies on battery monitor data.
A stored P058A code may be the only sign, with the vehicle starting and running normally.
In some cases, the charging system may default to a fixed voltage, reducing fuel efficiency or battery life.

Common causes, most likely first

A failing or internally faulty battery monitor module, often due to heat, vibration, or water intrusion.
Corroded, loose, or damaged wiring and connectors between the battery monitor module and the battery, body ground, or data bus.
A weak or aging 12-volt battery that causes the monitor to report implausible data and set a performance code.
Software or calibration issues in the battery monitor module or engine control module requiring a reprogramming update.
Poor ground connections at the battery negative terminal or chassis, leading to voltage drop that confuses the monitor.
A faulty current sensor or voltage sensing circuit inside the battery monitor module.
Communication faults on the controller area network (CAN) bus that intermittently disrupt data from the battery monitor module.

How to diagnose and fix it

Perform a thorough visual inspection of the battery, its terminals, and all ground straps for corrosion, looseness, or damage.
Test the 12-volt battery with a conductance tester and verify its state of health and charge; replace it if it fails.
Check the battery monitor module's wiring harness for chafing, pin fit, and continuity to ground and power, repairing as needed.
Clear the code and perform a test drive to see if P058A returns; if it does, follow the manufacturer's diagnostic flow for the battery monitor module.
Check for technical service bulletins or software updates for the battery monitor module or engine control module and reprogram if applicable.
If all wiring and battery tests pass, substitute a known-good battery monitor module and recheck for the code.
After any repair, clear codes and verify that the battery monitor module communicates properly and that no pending codes return.

Battery Monitor Module Faults You Might Overlook

A weak or failing 12-volt battery is a common root cause of P058A because the monitor's calculated data becomes implausible when the battery cannot hold a stable charge.
Corroded ground connections at the battery negative terminal or chassis can create voltage drops that the battery monitor interprets as an internal performance fault, even when the module itself is fine.
Some vehicles set P058A after a battery replacement if the battery monitor module is not reset or reinitialized according to the manufacturer's procedure.
Intermittent CAN bus communication faults can cause the engine control module to lose contact with the battery monitor module and store P058A, so always check for other communication codes.
The code does not always mean the battery monitor module is defective; a charging system fault or a parasitic draw that keeps the battery at a low state of charge can also trigger it.

Can I keep driving with P058A?

You can generally continue driving with P058A, but avoid long trips or relying on the vehicle for critical journeys until the fault is diagnosed, because a failing battery monitor can lead to a no-start condition or reduced charging system performance. If the battery warning light is also on or you notice slow cranking, have the charging system checked promptly.

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.