rhino1616

I have a 2002 protege5 & the front O2 sensor is broken. Im shopping online but I notice there are different ones IE:

1)Oxygen Sensor = Univeral Type, 2 Wire 20cm Long, w/o Connectors
2)Oxygen sensor = Universal Type, 4 Wire, Without Connectors
3) are the back & front O2 sensors different?

which is the correct one the 2 wire or 4 wire? & they sell without the connector, is that a big deal? cant I just use the old connector & attach it on to the new one?

Thank you

HopefulFred

I don't know how many wires it should have, but you need to trace the wire from the sensor to the connector and count them. I strongly suspect that it will have 4 wires - two for the "sensor" function of the sensor, and two for the heater circuit. Typically a factory installed set of sensors with be different front to rear because the wiring lengths will need to be different. I don't know if the signals generated by the sensors are different, but I think they are probably the same.

My suggestion would be to source an OE fit sensor, not a universal design that will require splicing wires. I know the universals are a lot less expensive, but how many times do you want to cut into your Mazda's expensive wiring harness, risking cross-wiring and opening things up to corrosion and faulty connections? The proper sensor will come ready with the right length wire and the pig-tail clip that will just clip in like the OE on the vehicle now.

Call Advance or O'Reilly's or whoever is near-by (or use their website). Get the part number and a picture from the website and comparison shop if you like. According to Advanceautoparts.com the Bosch pn's for upstream (front) oxygen sensor for a 2002 Protege5 is 13870 and costs about $250. (It is heated - 4-wire as I suspect the OE is in the vehicle now. In fact there is a fair chance that Bosch is the OEM; someone else around here could probably say for sure) I think you can find that same Bosch sensor elsewhere on the internet for less but I would call and ask them to confirm the Bosch pn before you buy.

Are you 100% sure you need a new sensor and there is not something else going on? Proper diagnosis of a faulty sensor requires some sophisticated equipment, unless the heater circuit is the faulty part - in which case you should still unplug the sensor and check the resistance of the heater circuit against the spec in the repair manual before you bother risking stripping the threads out in your exhaust system on a guess - not to mention the money.

Fred