Check engine light - oxygen sensor gen3

[B-Man]

Had a check Engine light and scanned as the left hand oxygen sensor.
Have replaced it but it still comes up about 5 minutes into the drive.

On a long drive it has disappeared once but comes back the next day.

Got it on the scan tool and shows this below.
Any pointers on fixing it?
What's not ready mean?
The left always stays around the 440mv
Right had dropped down when revved up and back to the 880mv on idle

 

[gtrboyy]

Swap sensors over if values are not the same then you know it's a wiring issue.

Supposedly common for them to get water/moisture in harness plug & play up if not mounted correctly.

 

[B-Man]

Will try that when I can get on the hoist.

Plug looks good. Not wet at all.

Tested the wiring
Pink 12v+ (heater) (4.3ohms testing o2 sensor heater wires)
Black-red ground ?
Purple signal hi+ 1.22v?
Blue/grey? Signal low - has continuity to pcm

Is heater ohms low? From googling I saw someone said ~14 ohms?

 

[B-Man]

Serviced the car Yesterday and decided to chuck 2 new O2 sensors in it and still has the same problem...
at a loss. anyone got any other solutions?

Im assuming bank 1 is left and is the passenger side?

 

[BlackVXGTS]

Im(sic) assuming bank 1 is left and is the passenger side?

Yes, for RHD cars (ie. ours in Australia).

 

[Jolls]

I would start with the earth (BK/RD). It is earthed directly back to the PCM; however, if the PCM was poorly earthed you would be getting heaps of other problems showing up. The earth is common to both so you should be able to rule it out given the other sensor is working fine. Check the wiring for rubbing - earth leakage through an abraded wire is a possibility.

12V at the heater wire should be exactly what you need. Can't see a problem there.

Purple high at 1.22V seems odd. Should be 450mV out of the PCM with nothing connected. May want to check this on both sensors (the other one is gray) and compare. The 1.22V is at odds with the 446mV reading on the scanner.

446mV stable in operation is where the problem lies. For some reason this is not being affected by the sensor. This would usually indicate a sensor fault and probably point to the heater.

Have you checked the heater ohms on both sensors to compare? I think this would be a valuable step.

Swap them around see if the problem moves.

Let us know how you go.

Cheers n Beers
Jolls

 

[B-Man]

Started from scratch

No damage to wiring that I can see. It all still wrapped up in the black corrugated stuff.

Heater has 12v earthed to the (BK/RD) in the plug.
New sensor was around 5 ohms
Plugged one of the old o2 sensors on and it got very hot.
So I'm going to assume heater works.

I get 193mv on the sensor wire... with ignition on and car running/ not running
Not sure how I got that last reading. ‍

Conclusion the earth's work and the heater and sensor wire works...

Don't have access to the computer atm to see what is reading.

Can't see any exhaust leaks before the sensor. Has genuine headers and exhaust.

 

[Jolls]

Started from scratch

No damage to wiring that I can see. It all still wrapped up in the black corrugated stuff.

Heater has 12v earthed to the (BK/RD) in the plug.
New sensor was around 5 ohms
Plugged one of the old o2 sensors on and it got very hot.
So I'm going to assume heater works.

I get 193mv on the sensor wire... with ignition on and car running/ not running
Not sure how I got that last reading. ‍

Conclusion the earth's work and the heater and sensor wire works...

Don't have access to the computer atm to see what is reading.

Can't see any exhaust leaks before the sensor. Has genuine headers and exhaust.

So the basics are covered, although 193mV on the sensor wire seems too low for me. It is time to dig out the manual and follow the diagnostic tables. I have printed to pdf and attached the relevant section for you to digest.

Before you try to fault find make sure you check the warning below

I trust that this guide gets you on route to a solution.

I am very interested to see what your diagnosis and solution is. Hopefully not a new PCM.

Cheers n Beers
Jolls

Cheers n Beers
Jolls

 

[B-Man]

Cheers I'll have a look

 

[B-Man]

Haven't had time to look at that yet.
But noticed something else.
Had the ignition on but hadn't started it and the engine light come on after about 5 minutes.

Can't see anything engine related that would be causing it if it's not running. Makes me think it's something wrong with the computer ?