The engine P2820 code seems a kind of powertrain problem and this is a general problem of the car engine. You may use this meaning of the code and it is p for Powertrain Code Problem is related engine, transmission and emissions systems. 2 for MFG – Manufacturer Specific. 8 for Ignition System Or Misfire. 2 for Air Conditioning (A/C) Clutch Feedback Circuit High Voltage and 0 for Transmission Engaged At High Throttle Angle. The engine P2820 code seems a kind of powertrain problem and this is necessary to solve the car engine properly. If you do not know the way of solving the car engine, you need to depend on a technician.