P058B code meaning
Battery Monitor Module Current Monitoring Performance
Powertrain system Generic code P05xx codes Check engine light
What P058B means
The battery monitor module (intelligent battery sensor) sits on the negative terminal of the 12 V battery: a shunt measures current, electronics also measure voltage and temperature and calculate state of charge, health and cranking ability, reporting over LIN. Energy management uses the data for alternator control, idle boost and stop-start release, which is why the engine module diagnoses it. GM sets P058A–P058F in its engine modules from 2016 as type B, warning lamp after two trips. P058B concerns current measurement. In the sensor variant the module itself reports implausible current; GM's eAssist and stop-start engines compare it with their own reference and set it at 22 A difference in 160 of 200 samples. GM bulletins for the 2014–16 Malibu and Impala name a ground ring lying on the sensor's shunt or a loose terminal – current then bypasses the shunt.
P058B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.2 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P058B
- Check engine light, often sporadic
- Stop-start inactive
- Wrong state of charge display or battery warning
Common causes of P058B
- Most likelyGround ring touching the shunt or loose
- PossibleFretting corrosion in the sensor connector, loose ground splice
- PossibleBattery sensor faulty
- Less likelyRetrofitted loads grounded directly at the negative post
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Battery monitor moduleBattery terminalLin busEngine control module
What each part of P058B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 8B | The exact fault in that area. |
What to do next
- Note P058B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P058B
What does P058B mean?
P058B means "Battery Monitor Module Current Monitoring Performance". The battery monitor module (intelligent battery sensor) sits on the negative terminal of the 12 V battery: a shunt measures current, electronics also measure voltage and temperature and calculate state of charge, health and cranking ability, reporting over LIN. It is a generic code, so it means the same on every make.
Is it safe to drive with P058B?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P058B fail an emissions test?
Yes, it can. P058B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P058B to fix?
Difficulty: easy. A typical repair takes 0.2 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P058B clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.