MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: kerbut on May 10, 2018, 19:31

Title: 4 wire and 2 wire O2 sensors
Post by: kerbut on May 10, 2018, 19:31
 Can a 4 wire o2 sensor be used in place of a 2 wire ?, ie would 2 of the wires in the plug mate up with the 2 correct wires on the sensor. I can find plenty of 4 wire ones on Ebay but not 2 wire. I realise the wire is longer on a 4 wire.

MOD all MR2 O2 sensors are 4 wire, the 2 manifold sensors are the same, the post cat sensor is different, it has longer wires but still 4
Title: Re: 4 wire and 2 wire O2 sensors
Post by: jonbill on May 10, 2018, 20:03
Why do you want a 2 wire sensor? Mr2s use 4 wire.
Title: Re: 4 wire and 2 wire O2 sensors
Post by: StuC on May 10, 2018, 20:24
Just looked on Banana.

Manifolds are 4...
(https://uploads.tapatalk-cdn.com/20180510/b74367ca89568f2fbc8266bb88a1f29c.jpg)

My post cat is 4 too...
(https://uploads.tapatalk-cdn.com/20180510/5e4810f2675d48d36273ff3d9acea8bb.jpg)

Didn't realise the post cats had 4 wires.
In which case the connector is likely to be identical. Haven't tried it though.
Title: Re: 4 wire and 2 wire O2 sensors
Post by: StuC on May 10, 2018, 20:52
All 4 wires. All sensors.

I was getting confused, as the heater circuit in the post cat is not as important as the ones in the manifolds. There is a fix for a broken post cat sensor heater circuit, which puts a big assed resistor in the circuit (essentially replacing the heater). 


Mod Edit
Tidied up a little as requested

8)
Title: Re: 4 wire and 2 wire O2 sensors
Post by: stewart@boro on May 10, 2018, 22:10
Too many Stu's/Stew's on the job ;)
Title: Re: 4 wire and 2 wire O2 sensors
Post by: StuC on May 10, 2018, 22:16
Stew's to the rescue. Thanks chaps. :)
Title: Re: 4 wire and 2 wire O2 sensors
Post by: jonbill on May 10, 2018, 22:36
Good to know I remembered something right [emoji851]
Title: Re: 4 wire and 2 wire O2 sensors
Post by: kerbut on May 12, 2018, 14:50
Thanks, everyone for the help, I bought 2 cheap o2 sensors (£13.26 each ) from Ebay and a replacement for the post cat from Rutland MR2, fitted them all today, disconnected the battery while I had lunch to reboot the ECU, reconnected and the light went out and has stayed out after 10 miles driving it quite hard. The wires were different colours on the cheap sensors(ie white joins to black) but I found a conversion chart on the internet at a site called Stack Exchange.


Edit to add: the bloody light has come on again about a mile after I added cat cleaner, I have now disconnected the battery again and in the morning reconnect it and see how many miles I do before it comes on again as I have a cunning plan if it does. On the day of the MoT before the test disconnect battery around the corner wait, 15 minutes reconnect and drive to test station and the light should be out for the duration of the test !.
Title: Re: 4 wire and 2 wire O2 sensors
Post by: m1tch on May 14, 2018, 16:13
Quote from: kerbut on May 12, 2018, 14:50
Thanks, everyone for the help, I bought 2 cheap o2 sensors (£13.26 each ) from Ebay and a replacement for the post cat from Rutland MR2, fitted them all today, disconnected the battery while I had lunch to reboot the ECU, reconnected and the light went out and has stayed out after 10 miles driving it quite hard. The wires were different colours on the cheap sensors(ie white joins to black) but I found a conversion chart on the internet at a site called Stack Exchange.


Edit to add: the bloody light has come on again about a mile after I added cat cleaner, I have now disconnected the battery again and in the morning reconnect it and see how many miles I do before it comes on again as I have a cunning plan if it does. On the day of the MoT before the test disconnect battery around the corner wait, 15 minutes reconnect and drive to test station and the light should be out for the duration of the test !.

Is the engine code for the O2 sensor or the O2 sensor heater?
Title: Re: 4 wire and 2 wire O2 sensors
Post by: jonbill on May 14, 2018, 17:40
Tbh I've tried cheap ebay sensors and they only lasted a few days. Or could be the cat cleaner.....