P0BAB code meaning
Hybrid/EV Battery Voltage Sense W Circuit Low
Powertrain system Generic code P0Bxx codes Check engine light
What P0BAB means
A W channel reading at or near zero sets P0BAB. How low is too low depends on the battery: GM's lithium-ion modules of 2016 and 2019 react to 0.2 V or less held for 1.4 s within a 2 s window, Type A, and the 16OBDG02 programme to under 0.20 V in 14 of 18 samples at 100 ms. The eAssist mild hybrid already fails below 1.4 V, seven of ten samples, as long as the 12 V supply exceeds 8.8 V and P1B38 is not active; that fault is Type B. All of these tests stand down while an open sense line fault is present, so a simply broken lead shows up as P0BA9. P0BAB on its own suggests a short towards a lower potential, a dead measuring input or a deeply discharged cell. Power and charging are usually restricted.
P0BAB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0BAB
- Hybrid or EV warning and MIL
- Reduced power output
- Charging limited or blocked
Common causes of P0BAB
- Most likelySense lead W shorted to a lower cell potential
- PossibleMeasuring input for W on the monitoring board failed
- Less likelyCell W deeply discharged or internally shorted
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery voltage sense wWiring harnessBms
What each part of P0BAB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B | Area: hybrid propulsion. |
| AB | The exact fault in that area. |
What to do next
- Note P0BAB 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 P0BAB
What does P0BAB mean?
P0BAB means "Hybrid/EV Battery Voltage Sense W Circuit Low". A W channel reading at or near zero sets P0BAB. It is a generic code, so it means the same on every make.
Is it safe to drive with P0BAB?
Drive gently and only to a workshop. With P0BAB the car can go into limp mode (reduced power) to protect itself.
Will P0BAB fail an emissions test?
Yes, it can. P0BAB 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 P0BAB to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0BAB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.