P0ADDHybrid/EV Battery Negative Contactor Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Vehicle will not enter ready mode or start
- Hybrid or EV warning light and check engine light
- Charging not possible
- Likely causes
- LikelyOpen in negative contactor coil or its pigtail
- PossibleLoose or corroded connector at the battery disconnect unit
- PossibleBroken control wire in the battery harness
- RareDriver in the battery controller defective
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.