daviddevt

Code P0031 needs a B1S1 O2 Sensor..... Is it the one reached under the car just before the catalytic converter or on the front of the engine?

robbyk

Bank 1 Sensor 1 is on the side of the engine closest to the windshield. Carefully inspect the electrical connector for any loose, broken or damaged wires. If the visual inspection checks ok, replacing the correct sensor will solve the problem. These are actually extremely well-known high fail rate items.

This should help

daviddevt

Thanks for the reply and the pic.
I slid under the car and found a sensor facing down that appeared be before the Catalytic converter.... but the pic shows it on top. Am I seeing that right? and to I access from below the vehicle?

Thanks,
Dave

robbyk

That is correct, you have an oxygen sensor before the Catalytic but you also have an oxygen sensor on the exhaust manifold as shown on the picture. The way to get to it is to first secure the vehicle on jack stands, put a jack under the engine with a 4x2 piece of wood. Loosen up the center engine mount, drop the engine slowly, then under the car you can reach the oxygen sensor. It is extremely tight but doable.

AussieAuto

Make sure you get the correct sensor it is an air/fuel ratio sensor not oxygen sensor. Robbyk is right you can get it from underneath once you crack it (22mm wrench or socket) it should unscrew pretty easily. Try getting a Denso sensor as that is the genuine one that Lexus uses...