P0ADD code meaning
Hybrid/EV Battery Negative Contactor Control Circuit/Open
Powertrain system Generic code P0Axx codes Check engine light
What P0ADD means
The negative main contactor closes the return path of the traction battery; P0ADD reports an open in its coil drive circuit. GM documents the code in parallel to the positive side: tables since model year 2011 detect open load in the HPC2 and store it after two trips; 2016-19 tables evaluate a control voltage between 1.15 and 2.81 V while off, 40 of 50 samples, Type B, and 2019 tables add a coil current check below 194 mA when on. CARB 1968.2 covers this circuit monitoring of hybrid components. Related codes are P0ADF and P0AE0 for low and high, P0AA5 for a contactor stuck open, P0AD9 for the positive side. Without this contactor the HV system stays off.
P0ADD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0ADD
- Vehicle will not enter ready mode or start
- Hybrid or EV warning light and check engine light
- Charging not possible
Common causes of P0ADD
- Most likelyOpen in negative contactor coil or its pigtail
- PossibleLoose or corroded connector at the battery disconnect unit
- PossibleBroken control wire in the battery harness
- Less likelyDriver in the battery controller defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery neg contactorWiring harnessBms
What each part of P0ADD 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. |
| DD | The exact fault in that area. |
What to do next
- Note P0ADD 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 P0ADD
What does P0ADD mean?
P0ADD means "Hybrid/EV Battery Negative Contactor Control Circuit/Open". The negative main contactor closes the return path of the traction battery; P0ADD reports an open in its coil drive circuit. It is a generic code, so it means the same on every make.
Is it safe to drive with P0ADD?
Drive gently and only to a workshop. With P0ADD the car can go into limp mode (reduced power) to protect itself.
Will P0ADD fail an emissions test?
Yes, it can. P0ADD 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 P0ADD to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0ADD clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.