I got a P0130 code for bad O2 sensor Bank 1, Sensor 1. I bought the sensor from the dealer at 6 times the aftermarket price. I see the two sensors before and after the Cat near the radiator but this one is suppose to be near the firewall. I removed the plastic cowl but can't find them. Do I need to remove the manifold or are they accessible from under the car? Anyone got a photo showing where this one (Bank 1, Sensor 1) is located?