P0AA0 Possible Causes
- Faulty system main relay
- System main relay harness is open or shorted
- Poor electrical connection in the system main relay circuit
- Faulty HV control ECU
What Does It Mean?
How to Fix Code P0AA0
Check the “Possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0AA0 Possible Symptoms
Check engine light illuminated (or service engine soon warning light)
P0AA0 Meaning
The SMRs (System Main Relays) connect and disconnect the high voltage power circuit according to requests from the HV control ECU. To ensure reliable operation, they consist of a total of 3 relays (1 for the negative side and 2 for the positive side).
To connect, SMR1 and SMR3 initially turn on. Then, SMR2 activates and SMR1 turns off. This process protects the circuit from high voltage inrush current by allowing limited current to flow through the resistor. To disconnect, SMR2 and SMR3 turn off in that order. The HV control ECU verifies that the relays have properly closed.
The HV control ECU monitors the proper operation of the SMRs (CON1, CON2, and CON3) to check for malfunction.