Problems with CO2 sensor

[Daniel33]

Hi everyone.

I am new here, and getting nowhere. I searched for solutions, but nothing came up.

I have a Forester. 2006, throwing the famous P0031 code.

I researched the net for solutions, but came up empty. I did find one site which described where the main relay is, so searched out that, and found the CO2 heater circuit relays next to it.

I traced the wiring back to the relays, and they are fine. The sensor itself is fine. Where does the power come from for the large round relay though, as it is not getting any power to the switched side when the key is on?

I would appreciate any help. I only have a few hours left to get the roadworthy.

I would take it to a workshop, but can't afford it. I am in Australia, and used car ownership is strongly discouraged.

Please move this to any appropriate place. I will keep checking for replies.

Thanks in advance.

I am willing to share what I have learnt so far with others, if there are indeed any people out in the wider world that actually get their hands dirty anymore.

[Mark D]

There are different parts to the sensor, with 3,4,5 wires.

One measures the O2 (not CO2) in the exhaust compared with outside air

The other part is the heater.

Check that you have the correct o2 sensor with the correct wire colours from the sensor mating those from the car end.

If your car has two sensors, that should refer to the one before the cat.

I think the heater circuit is made so that any break in it, the Ecu detects that and not what is going on with the 02 readings.

Could be just the wrong sensor, right sensor but different wiring to the plug.

When I got my windscreen replaced I asked the mechanic to have a quick look at the o2... he said looking at the wire colours the plug should be the other way round! Universal sensors..

 

 

Sent from my iPad using Tapatalk

[Daniel33]

Hi Mark.

Thanks for the reply. The issue was not with the sensor. It ended up being with the plug connections. I also had difficulty getting the check engine light to stop coming on, but got it worked out now.

Thanks.