How many O2 sensors r on an 08 Prius, are they easy to change?

I have an 05 Prius and I have covered 130,000 miles I still get great fuel consumption but would also like to know. I thought there was just the one and don't fix what isn't broke

 

The Prius has an air/fuel ratio sensor upstream from the catalytic converter and an oxygen sensor downstream from the cc. If you need to replace them the correct Toyota parts would be best because you won't have issues with wiring harness connector fit, trying to splice a universal sensor into the existing connector, etc.

You may have to remove the inverter for access to the upstream A/F ratio sensor.

 

Patrick, you advised me on the upstream. The "may" is definitely correct. Big hands and not much flexibility might be a problem. I found the upstream to be accessible without inverter removal. You do have to remove the windshield wipers, wiper tray, and basically everything on the rear top firewall to get to it. I ended up "breaking" the seal from the bottom, but thread it in from the top and torqued it from the bottom again. It was less than a 2 hour job.

 

Bank 1, Sensor 2 is the O2 sensor which is downstream from the catalytic converter.

Bank 1, Sensor 1 is the A/F ratio sensor which is upstream from the catalytic converter.

 

I assume that you have logged an engine ECU DTC which points to the oxygen sensor?

The oxygen sensor will not be too hard to replace since it is downstream from the catalytic converter. You just need jack stands or some other safe means to raise up the car so you can get under it, and you will need an oxygen sensor socket and the appropriate 1/2" socket wrench and extensions as necessary. If the sensor binds in the threaded opening you may need to apply the special thin lubricant which hopefully will penetrate the threads and make the sensor easier to remove.

You'll also need to remove the center lower console area under the instrument panel and lift the carpet to access the wiring harness connector for the oxygen sensor. Then you can push the sensor wires out of the car for removal when the sensor is unscrewed.

Consult techinfo.toyota.com for factory repair manual info.

 

The 12V battery does not need to be disconnected but a benefit of doing so is that will clear any DTC logged by the engine ECU.

If the new sensor is working properly, there are no codes to be logged.

 

Good Morning Patrick. I have a question. Do you think this sensor you are talking about would make my engine rattle when I’ll step on the gas. It rattles more when my battery is low at 2 bars. What do you think it might be?

 

Usually a rattle is caused by something loose. If you have an engine ping or knock, that should be differentiated from a rattle.

 

The Toyota sensors are made by Denso, use ONLY Denso or Toyota especially the front sensor. A special tool is needed for the front sensor but people here have made their own. Use the search feature in the gen 2 threads for O2 sensor replacement and you should find a few how to’s. 48 bucks plus shipping at rock auto

2006 TOYOTA PRIUS 1.5L L4 ELECTRIC/GAS Oxygen (O2) Sensor | RockAuto

117 plus shipping if you want the Denso part in a Toyota box.

2006 Toyota Prius Base HYBRID Sensor, oxygen. Electrical, sensors - 8946547070 | Roseville Toyota, Roseville CA