P0AA1 fault code: what it means

P0AA1: BYD (SAE code): hybrid battery positive contactor stuck closed.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

welded contactor
BMS

P0AA1 by make

BYD

BYD (SAE code): hybrid battery positive contactor stuck closed.

Usual causes: welded contactor; BMS

Lexus

Hybrid battery positive contactor stuck closed on a Lexus hybrid: the main HV relay has welded and does not open at switch-off.

Usual causes: welded system main relay in the battery junction block; relay drive fault

Toyota

Hybrid battery positive contactor stuck closed: the main high-voltage relay has welded shut and does not open at switch-off.

Usual causes: welded system main relay (SMR) in the battery junction block; relay drive circuit fault

What the repair usually costs

Hybrid battery reconditioned exchange (Aqua / Prius C / Axio / Fielder)NZ$1,360–NZ$2,430 · A$1,390–A$2,370
Hybrid battery reconditioned exchange (Prius 20 / 30 / Prius alpha / Prius V)NZ$1,640–NZ$2,790 · A$1,880–A$3,550
Hybrid battery reconditioned exchange (Camry / Estima / Lexus / RAV4)NZ$2,140–NZ$4,150 · A$2,650–A$5,000
Hybrid battery new aftermarket (Aqua / Prius C)NZ$2,080–NZ$3,010 · A$2,350–A$3,610

Not sure what P0AA1 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.