Thread: O2 sensors

Check engine light came on the other day and a scan showed faulty forward sensors. Went to my local parts store and the sensors they showed were different (orange connector), the one they had for the rear was the correct/similar connector for the front, so I took those instead as I thought their inventory system had screwed up the parts.

Sensors were fitted to the front and a couple days later the light came back for one of the sensors faulty. I am now realizing that both front and back sensor on the truck has the same (grey) connector.

QUESTION - Is there a difference between the front and rear O2 sensor or are they the same and it is just different signals sent to the front and the back by the ECU.

Australian vehicles dont have rear sensors, they are a US spec only item. They don't affect the EFI, they only check the serviceability of the cats.

Also, older GEMS engines use a 0v-5v signal on the O2 sensor whereas THOR engines use a 0v-1v spread on the sensor. I believe it is wide band vs narrow band O2 sensors. So I think genuine items really are worth the money here and make sure you get the right part number for your VIN. Also, it is easy to check the O2 sensors values in real time using generic fault code readers or an ODBII adaptor and a smartphone app. They should cycle from 0v to 1v (mine only actually do 0.1v-0.9v) regularly as it is idling as it continuously changes the short term fuel trims based on the O2 readings. If they are not cycling like this swiftly, then you will have a bead on which is faulty.

Good thread on the RRnet main site.