DTC P0171 Or P0172: System Too Lean/Rich: Notes

WARNING: This page is about a different car, the 2000 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.

NOTE: Bank No. 1 refers to bank which includes cylinder No. 1. Bank No. 2 refers to bank without cylinder No. 1. Heated oxygen sensor No. 1 refers to sensor closest to engine block.