CEL came on recently. This is a 2000 Avalon. Codes of P1130 and 1135 were pulled. This points to the upstream O2 sensor, bank 1 sensor 1. Problem is, I replaced this one about 1-1.5 years ago. I pulled the "old" sensor and was going to clean it, but have managed to strip the threads on it when removing it. So I go buy an new sensor and install it. CEL is back on again. I'm about to sell my Toyotas and never buy another one again....I've had enough of the CELs and the O2 sensor failures. I'm $300 into this sensor, and the CEL is still on saying it's the same sensor!