T5 T5 1999 S70 T5 O2 Sensor errors. Need advice Topic is solved

Post by **Eddystone** » 05 Mar 2019, 23:42

My code reader says:

P0036 HO2S Heater Control Circuit (Bank 1 Sensor 2)
P0136 HO2S Sensor Circuit Malfunction (Bank 1 Sensor 2)

I posted this a while back but really need to fix it, now.

I can try cleaning the plugs, if I can located them. The ones I have found are under the intake manifold, and that doesn't make sense to me...

I'm looking at the Volvo Oxygen Sensor - Bosch 9497345 at the FCP site which it ID's as the downstream/rear sensor

I've watched Robert's video and FCP video and read a couple of threads with pics, and there seems to be some variation as to the plug locations and wire routing between models. Some photos may be for later years (unspecified).

What I'd like to know is: With my 2.3 T5 engine, where are the plugs where the wires from the sensors connect?

Do any of you replace these sensors as a preventive measure? My car gas 156kmiles on it.

If you buy a Bosch sensor w/o the plug and make a sound splice connection, is it reliable?

If I'm doing the rear sensor, should I go ahead and do the front sensor, too?

Thanks, people.

Post by **precopster** » 06 Mar 2019, 00:54

The connectors for both O2 sensors are usually close to the firewall on a bracket held at the rear of the transmission amongst the jungle of ABS lines. They are best sprayed with WD40 as they are often held together by grit and the release on them needs to slide easily. I haven't tried a cut splice version so can't comment.

Post by **Eddystone** » 06 Mar 2019, 01:18

precopster wrote: ↑06 Mar 2019, 00:54 The connectors for both O2 sensors are usually close to the firewall on a bracket held at the rear of the transmission amongst the jungle of ABS lines. They are best sprayed with WD40 as they are often held together by grit and the release on them needs to slide easily. I haven't tried a cut splice version so can't comment.

The Bosch OEM plug type is $81.
Splice yourself with their hi-tech connector is $41.

Post by **abscate** » 06 Mar 2019, 04:27

You will need a good tool to remove an original OXS, they get rusted in pretty good.

The three types of tool are

Split socket to allow the wire in
Dedicated split tool
Crows foot type socket allowing more torque access

Start hitting it with PB a week before removal, if you can let the car sit during that time.

Check the fuse and wire for chafe damage before replacing, although If you are running the car for 300k then replacement is recommended. Some feel the OXS get tired at 100k and can lead to lean running.

Post by **Eddystone** » 06 Mar 2019, 08:11

abscate wrote: ↑06 Mar 2019, 04:27 You will need a good tool to remove an original OXS, they get rusted in pretty good.

The three types of tool are

Split socket to allow the wire in
Dedicated split tool
Crows foot type socket allowing more torque access

Start hitting it with PB a week before removal, if you can let the car sit during that time.

Check the fuse and wire for chafe damage before replacing, although If you are running the car for 300k then replacement is recommended. Some feel the OXS get tired at 100k and can lead to lean running.

Already checked the fuse you wrote about and the others while I was there.

Post by **abscate** » 07 Mar 2019, 04:04

Going to be in philly week after next for a few days. Do have those OXS tools, pm me if interested in coordinating

Post by **Eddystone** » 07 Mar 2019, 07:56

I'll private message you.

Post by **Eddystone** » 17 Mar 2019, 22:12

Replaced the downstream O2 sensor, and the car seems to run better (a bit more responsive and idles a little smoother).

Waiting to see if the CEL comes back due to some other reason...

Post by **abscate** » 18 Mar 2019, 04:20

Those codes will come right away if the heater circuit faults, so you’ve definitely made progress

I’ll have an extra cheese steak To jcelebrate