P2BC9 code meaning
Battery Charging System Positive Contactor B Control Circuit Low
What P2BC9 means
P2BC9 is the low-signal fault on the coil feed of plus-side charging contactor B: the module measures less voltage on that wire than its command calls for, most often because the wire touches ground or the output stage is being dragged down. With a high-side feed the coil is then starved and the contactor never pulls in, or the output stage trips its own protection. No manufacturer documents P2BC9 publicly. GM notes for its corresponding contactor A test on the Chevrolet Volt (P0D0A) that the open-circuit check cannot detect a short to ground, so this case needs a check of its own. CARB requires monitoring of the charging system on plug-in vehicles. Expect insulation rubbed through on the battery casing or moisture inside a plug. P2BCA is the high counterpart, P2BD0 the same fault on the minus side. That charging mode is then refused.
P2BC9 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2BC9
- Charging session does not start
- Charging fault message
Common causes of P2BC9
- Most likelyControl wire of contactor B shorted to ground
- PossibleMoisture or corrosion in a connector
- Less likelyCoil of contactor B internally shorted
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bcs pos contactor bWiring harnessBms
What each part of P2BC9 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| B | Area: hybrid propulsion. |
| C9 | The exact fault in that area. |
What to do next
- Note P2BC9 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 P2BC9
What does P2BC9 mean?
P2BC9 means "Battery Charging System Positive Contactor B Control Circuit Low". P2BC9 is the low-signal fault on the coil feed of plus-side charging contactor B: the module measures less voltage on that wire than its command calls for, most often because the wire touches ground or the output stage is being dragged down. It is a generic code, so it means the same on every make.
Is it safe to drive with P2BC9?
P2BC9 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P2BC9 fail an emissions test?
P2BC9 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P2BC9 to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P2BC9 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.