P0A0C code meaning
High Voltage System Interlock Circuit A Low
Powertrain system Generic code P0Axx codes Check engine light
What P0A0C means
The voltage sensed on interlock loop A is too low while the module drives the loop – typically an opened loop or a short to ground. GM documents it codegenau: in its 2016 HPC2 table P0A0C sets when the sensed interlock voltage stays below 30 % of the 5 V test signal in 2 of 2 samples (12.5 ms each) with the 12 V supply above 10.2 V; it is Type A, so the MIL lights after one trip. The 2011 Volt tables used a 10 % threshold. Mercedes-Benz model line 243 stores P0A0C00 in the DC converter and on-board charger as a short to ground in the interlock circuit. The opposite fault is P0A0D. Since the loop guards against live HV parts, the system drops the contactors and the car will not drive on electric power.
P0A0C at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0A0C
- Check engine light (GM Type A) and hybrid/EV warning
- No ready mode, electric drive unavailable
- Charging may be blocked
Common causes of P0A0C
- Most likelyHV connector, cover or service disconnect open, interrupting the loop
- PossibleInterlock wire shorted to ground, e.g. chafed at a module or the body
- PossibleCorroded or pushed-back interlock pins
- Less likelyFaulty interlock source or sense stage in the battery or hybrid module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv interlock loopHv service connector
What each part of P0A0C means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| 0C | The exact fault in that area. |
What to do next
- Note P0A0C 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 P0A0C
What does P0A0C mean?
P0A0C means "High Voltage System Interlock Circuit A Low". The voltage sensed on interlock loop A is too low while the module drives the loop – typically an opened loop or a short to ground. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A0C?
Drive gently and only to a workshop. With P0A0C the car can go into limp mode (reduced power) to protect itself.
Will P0A0C fail an emissions test?
P0A0C 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 P0A0C to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P0A0C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.