P2D78 code meaning
Battery Charger Control Module B Processor Performance
What P2D78 means
P2D78 points at the processor inside the control module of charger B: its self-tests of program or working memory have failed, so the module no longer trusts its own computations. All other functional faults of that module belong to P2D77. No manufacturer documents P2D78 publicly. The kind of test meant is visible in the A-side twin P0E5E, for which Mitsubishi's 2023 PHEV code table names two triggers in the charger controller: a failed CRC check of the ROM and a failed RAM write/read test. CARB requires plug-in hybrids to detect charger malfunctions that disable charging or reduce charging performance. A charger that cannot vouch for its processor will not switch grid power into the battery, so charging is refused. Reprogramming may clear a corrupted memory image; a hardware fault means a new charger.
P2D78 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2D78
- Plug-in charging is refused right after connecting
- Charging system warning in the cluster
Common causes of P2D78
- Most likelyMemory or processor hardware in the charger B control unit defective
- PossibleCorrupted charger software, e.g. after an interrupted update
- Less likely12 V supply dip while the charger boots
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Battery charger cm bOn board charger
What each part of P2D78 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 78 | The exact fault in that area. |
What to do next
- Note P2D78 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 P2D78
What does P2D78 mean?
P2D78 means "Battery Charger Control Module B Processor Performance". P2D78 points at the processor inside the control module of charger B: its self-tests of program or working memory have failed, so the module no longer trusts its own computations. It is a generic code, so it means the same on every make.
Is it safe to drive with P2D78?
P2D78 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P2D78 fail an emissions test?
P2D78 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 P2D78 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P2D78 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.